Computer generated transcript

Warning!
The following transcript was generated automatically from the content and has not been checked or corrected manually.

Martha Jenkins Made by Natalja Woloncewicz – Year 3 Phase 1 and 2 lead Paediatric Society Natalja.Woloncewicz@student.Manchester.ac.uk – any questions on this case, other cases or Years 1 and 2, feel free to email me J Case 2, Sem 1 – Down Syndrome, Cell Division And Abortion Key Words of the Case – make sure you can describe what each are and their relevance. • Down syndrome • Fissions • Origins of replication • Trisomy • Gametes • Topoisomerase • Centromere • Nuchal translucency • Replication forks • Telomere • Quadruple test • Non-disjunction • Haploid • Polyploidy • AFP • Robertsonian translocation • Daughter cells • DNA helicase • Triploidy • hCG • Gonadal mosaicism • Growth phase I • Nitrogenous bases • Chromosome • S-phase • Antiparallel DNA • Tetraploidy • uE3 • Segment • Growth Phase II • 3’ end • Aneuploidy • Inhibin-A • 5’ end • Monosomy • Spina bifida • Sister chromatids • Mitosis • Nullisomy • Anencephaly • Cell division • Prophase • Leading strand • Patau syndrome • CVS • Mosaic down syndrome • Prometaphase • RNA primers • Mutation • Metaphase • DNA polymerase • Tetrasomy • Amniocentesis • Karyotype • Anaphase • DNA ligase • Insertion • NIPT • Lagging strand • Deletion • cffDNA • Edwards syndrome • Telophase • Inversion • Placental trophoblasts • Turners syndrome • Chromatin • DNA primase • Duplication • Abortion • Klinefelter's syndrome • Microtubules • Okazaki fragments • Epicanthic folds • Centrioles • RNAase H • Isochromosome • Hypotonia • Centrioles • DNA • Reciprocal Translocation • Meiosis I • Translocations • Single palmar crease • Poles • Combined test • Meiosis • Mitotic spindle • Meiosis ll • PAPP-A • Mitosis • Equatorial place • Histones • Germ cells • Kinesis • Chromatin • Free- b-hCG Down Syndrome The genetics of down syndrome – trisomy of the CHROMOSOME 21. – occurs in some or all of the individuals cells. 1. 95% of down syndrome cases are caused by non- disjunction of the chromosome 21. 2. 2% have a parent carrying Robertsonian translocation. 3. 2% have gonadal mosaicism where some of the egg or sperm are normal however some contain specific genetic chromosomal mutations. 4. 1% are due to other chromosomal rearrangement involving segment 21q22. Caused by chromosomal abnormalities - Non-disjunction of chromosome 21 - failure of chromosomes or sister chromatids In the exam you may get a picture of a to separate at anaphase in cell division. By Robertsonian karyotype like above with some different translocation. abnormalities and you should be able to identify the disorder e.g. down syndrome, Edwards, turners, Klinefelter etc. there are also Mosaic Down Syndrome – is where the mutation happens further on in development of the foetus and therefore those simple questions on the exam where you’re individuals have a mixture of normal cells and a mixture of asked what chromosome is affected when a trisomy 21. person has downs. Features Of Down Syndrome Mild/Moderate Learning Disability: Distinctive Facial Features • May have communication challenges • All Down Syndrome individuals don’t look the same • Difficulties in completing and • Flat facial features understanding simple and everyday • Bulging tongue tasks • Almond shaped eyes • Trouble learning new things • Epicanthal folds - An epicanthal fold is skin of the upper eyelid that covers the inner corner of the eye. The fold runs Health Problems: from nose to the inner side of the eyebrow. • Congenital heart defects • Low set ears • Gastrointestinal problems • Short neck • Hypotonia – an abnormally low level of muscle tone • Hearing and vision issues • Single palmar crease - A single transverse palmar crease is a • Hypothyroidism • Susceptible to infections single crease that extends across the palm of the hand, • More likely to develop dementia formed by the fusion of the two palmar creases Average Life Span – the average life span of an individual with down syndrome is approx. 60 years. Unfortunately, 5% of down syndrome babies won’t live past their 1st birthday.Cell Division Vs Mitosis ea rw ibncl Th sinonvey quepiaaroAy resiielImgo learwe DNA yhatddfr w stnd The Cell Cycle The cell cycle – split in 4 parts: P - Pronounced 1. Growth Phase 1 -mass of the cell increases as the new organelles and proteins are made. M - Middle 2. S – phase – DNA replication A - Apart 3. Growth phase 2 – cell continues to grow and the proteins needed for cell division are made. T – Two groups 4. Mitosis – PMAT and cytokinesis Prophase - The chromatin condenses Anaphase - The mitotic spindles attached to and coils into structures called Metaphase - Chromosomes align down the the centromeres of the chromosomes begin chromosomes. Mitotic spindle fibres middle of the cell at the cells equator/ to shorten. They pull the sister chromatids equatorial plane/ plate of the cell. This happens apart towards opposite poles of the cell in begin to form. Centrioles form and by motor proteins e.g. kinesis (which are which they briefly appear as a V shape. The microtubules radiate from centrioles proteins found on either side of a chromosomes as the centrioles move to opposite centromere) helping to move the chromosomes two split portions of the cell are officially poles of the cell. according to the opposite poles pull and known as ‘daughter chromosomes’ at this therefore moving them and creating a vertical point in the cell cycle. Prometaphase - The nuclear line of chromosomes down the centre of the cell. (known as either the metaphase plate or Telophase - The chromatids have now membrane/ envelope begins to separated to opposite poles of the cell. The disintegrate. This allows the the spindle equator).At this point in mitosis the two groups of daughter chromosomes are chromosomes to spread around the chromosomes are maximally contracted and so enveloped in nuclear membrane. Within the cell freely. Each of the chromosomes are more easily visible. Each chromosome gives newly formed nuclear membrane/nuclei the become attached at the centromere to the letter X shape. Where two sister chromatids chromosomes uncoil and return to their a microtubule of the mitotic spindle. are attached at the centromeres. chromatin state. S-Phase – DNA Replication LOOK OVER IN YOUR OWN TIME 1. DNA replication takes place at multiple points in the DNA called origins of replication/ consensus areas. 2. An enzyme called topoisomerase unwinds the tightly wound DNA. It does this by temporarily breaking the bonds in the backbone of the DNA so unwinding can happen than it reforms the bonds to maintain the structure. Key enzymes: 3. At the origins of replication, bifurcated Y-shaped structures know as replication forks appear – (this is the point where DNA 1. Topoisomerase – helicase starts). DNA helicase splits the hydrogen bonds between the complimentary nitrogenous bases. unwinds the DNA 4. DNA structure is antiparallel meaning that one strand is moving from the 3’ (prime) end to the 5’ (prime) end, yet the other 2. DNA helicase – breaks H-bonds between on is in the opposite direction and goes from the 5’ end to the 3’ end. When DNA replicates nucleotides can only be added Bases from 5’ to 3’ end. This strand of the DNA is known as the leading strand. 3. DNA polymerase – 5. On the leading strand RNA primers are added which allows the DNA polymerase to add nucleotides to the template strand of adds the new DNA. The nucleotides are then bonded together using the enzyme DNA ligase. nucleotides 4. DNA enzyme ligase – 6. When we synthesise the leading strand the formation of the complementary strand follows the direction of the DNA helicase binds the new bases to breaking the DNA up, ( a bit like a zipper closing). each other 7. However, we have another template strand which is in the direction of 3’ to 5’ end. This is called the lagging strand. As we 5. DNA primase – adds know we cannot add nucleotides moving from a 3’ end to a 5’ end. RNA primers 8. So as the DNA is broken by DNA helicase, DNA primase add RNA primers (usually around 10 nucleotides long) to the DNA. (so 6. RNAase H – RNA little sections of DNA are added) primers are removed 9. DNA polymerase then starts and the 5’ end and moves its way backwards to the 3’ in the opposite way of the DNA helicase. from the strands Theses sections/ fragments that are added are called Okazaki fragments. 10. RNA primers are removed by RNAase H. The fragments are then bonded together by an enzyme called DNA ligase. This process and the Attached at the end enzymes used are of this presentation is very high yield an excellent YouTube video on this whole questions and you process that you will get one on the should watch. enzymes! Meiosis Meiosis 1 Sometimes referred to as reduction division. This is because it is the meiotic division where the chromosome number is halved. 1. Prophase 1 - Chromosomes enter this phase split longitudinally into two chromatids which are joined at the centromere. However they still begin to condense and become visible. Homologous chromosome pairs (one form mum and one from dad) align directly opposite each other in a process known as synapsis. Each pair of homologous chromosomes is known as a bivalent. The bivalents tightly coil. Crossing over of chromosomes (recombination) occurs at points on the chromosomes call chiasmata. During this homologous sections/regions are exchanged between chromosomes. This creates genetic variability. The homologous recombinant chromosomes now begin to separate but remain attached at the chiasmata. Separation of the homologous chromosome pairs proceeds as the chromosomes become maximally condensed. 2. Metaphase 1 - The nuclear membrane disappears. Chromosomes become aligned on the equatorial plane of the cell where they have been attached to spindles, the same as in mitotic metaphase. 3. Anaphase 1 - Chromosomes now separate out to opposite poles as the spindles contract. This is done randomly which is known as independent segregation. 4. Telophase 1 - each set of chromosomes have now separated out. And each cell has 1 copy of either the maternal or paternal chromosome. Each cell has a diploid number (2N) Meiosis 2 The cell goes through the whole process again of PMAT however instead of the separation of homologous chromosomes it is the separation of sister chromatids into haploid daughter cells known as gametes. Structure And Function Of A Chromosome • They provide genetic variation for living organisms. • A chromosome is one long continuous thread of DNA. • DNA wraps around proteins called histones. • During Interphase, DNA and histones form chromatin that look like spaghetti. • Chromosomes condense tightly for mitosis. Centromeres – a functional chromosome must have one , and only one, functional centromere. 2 sister chromatids are joined by a centromere. Or strictly at the kinetochore of the centromere. The kinetochore is the attachment area of the spindle fibres that shorten and pull the chromatids to opposite poles of the cell. Telomeres – special structures at the end of chromosomes. Contain long arrays of tandemly repeated DNA sequences. When cells divide chromosomes lose roughly 10-20 repeat units. If the telomere is completely lost the chromosome becomes unstable normally leading to cell death. Telomeres have enough repeats to survive cell divisions that occur in the lifetime of a person. But between generations they need to be renewed. Germ-line cells Common and cancer cells contain and enzyme called telomerase that is able to restore telomeres to full length. questions on the definitions. Sister chromatids – replicated chromosomes that are genetically identical. Also be aware Attaching at the centromere. Pulled apart during anaphase of cell division. of chiasmata's. Chromosomal Abnormalities Chromosomal abnormalities are rather common. Around 7.5% of fertilised zygotes are created containing chromosomal structural abnormalities, however only about 0.6% are babies are born with them. The difference in the figures shows that most chromosomal abnormalities are lethal and only a few babies make it to term. Made by Natalja Woloncewicz – Yr 1 The 8 Key Words You Need To Know: • Polyploidy – A cell that contains a number of chromosomes more than 2n e.g. 3n = triploidy and 4n = tetraploidy • Triploidy – can arise from either an egg being fertilised by two spermatozoa which is called dispermy or by the fertilisation of a diploid gamete. 69 chromosomes • Tetraploidy – arises from the failure of completion of the first zygotic mitotic division and is incompatible with life. 92 chromosomes. • Aneuploidy – e.g. The different conditions of aneuploidy are nullisomy (2N-2), monosomy (2N-1), trisomy (2N+1), and tetrasomy (2N+2). The lose or gain of 1 or 2 chromosomes • Nullisomy - Nullisomy is a genome mutation where a pair of homologous chromosomes that would normally be present is missing. Thus, in Nullisomy, two chromosomes are missing, and the chromosomal composition is represented by 2N-2. Individuals with Nullisomy are referred to as Nullisomic’s. • Monosomy – is the loss of a chromosome. If there is a loss of the chromosome from chromosome pairs 1- 22 this is lethal and the baby will die, unless there are partial monosomies in unbalanced translocations and these genotypes may be viable. The only monosomy condition is the monosomy of the sex chromosomes called Turners Syndrome where the individual has only one X chromosome which is represented as X0. The individual possess only 45 chromosomes • Trisomy – is an extra copy of one of the chromosomes. For example the trisomy of chromosomes 21 is down syndrome and the trisomy of chromosome 18 is Edwards syndrome. The trisomy of the sex chromosomes forming XXY is called Klinefelter syndrome. XYY is known as Jacobs syndrome - Trisomy causes an individual to possess 47 chromosomes. • Tetrasomy - Tetrasomy is a type of aneuploidy where there is a gain of extra two chromosomes of the same type. The chromosomal composition is represented by 2N+2. In humans, tetrasomy would result when nondisjunction occurs during meiosis. The resulting tetrasomic gamete when involved in fertilization would eventually develop into a foetus with 48 chromosomes rather than the normal 46. E.g. tetrasomy 12p (Pallister-Killian syndrome), tetrasomy 22 (Cat eye syndrome), 48, XXXX syndrome, 48, XXYY syndrome. Key Conditions Other Than Down Syndrome You Need To Know Turners Syndrome Edward’s Syndrome Klinefelter’s Syndrome Trisomy chromosome 18 Only affects females – Males have an extra copy of the X when an X chromosome is chromosome so they will have XXY missing/ partially missing This is high yield – in the Sem 1 mid test there was a question to match up the diseases to the physical features. In the End Sem1 final there was a definition of Edwards syndrome. Non-Disjunction This can happen at either meiosis 1 or at meiosis 2. The first two pictures show non-disjunction in the chromosome 21 which can lead to down syndrome, this picture is also representative of what could happen to pairs 1-22 of chromosomes during meiosis. The second set of pictures shows non-disjunction in oogenesis (the production of the female oocyte/egg gamete). The third set of picture shows non-disjunction at the production of the male gametes known as spermatogenesis. Non-disjunction can also occur in mitosis not just in the production of gametes in meiosis. In a fully formed adult this is not considered an issue. However the timing of non-disjunction in early development is vital. In the early stages of embryo development if a non-disjunction mitotic division occurs large production of the cells that will begin to form the baby will be trisomic regardless of if the original gametes were trisomic to begin with. If enough cells or the majority of the cells in early development are trisomic the baby could express the phenotypic features of the trisomic cells for example Edwards syndrome or down syndrome. Therefore it is plausible to have downs individuals and individuals with Edwards syndromes to have a mixture of cells with 46 chromosomes and 47. Structural Abnormalities Structural abnormalities – caused by chromosomal breakages of 1 or 2 chromosomes. The rate of structural abnormalities is increased by exposure to mutagenic agents such as ionizing radiation and certain chemicals. Rate increased in certain inherited conditions with defects of DNA replication and repair e.g., Blooms syndrome. Structural abnormalities in SINGLE chromosomes: • Deletions - loss of a part of a chromosome • Inversions - inversion of a segment of a chromosome (paracentric inversions = does NOT contain the centromere. Pericentric inversions = do contains the centromere.) • Duplications - duplication of a chromosomal segment in tandem or in inverse configuration with the original sequence. (tandem duplication. The occurrence of two identical sequences, one following the other, in a chromosome segment.) • Isochromosome - duplication of one arm of the chromosome coupled with loss of the other arm so that chromosome consists of two identical arms. Structural abnormalities in TWO chromosomes: • Insertions - breakage of material from one chromosome and insertion into another chromosome. • Translocations - two types - reciprocal translocations and Robertsonian translocations The Combined Test • Screening test • 10-14 WEEKS Everything in the colour Red are very high yield • It is called Combined as it is both an ultrasound and a blood content. For those aiming for honours and distinctions it is good to know the false positive test. These can be done at the same time, usually at the 12 week scan. rates. • The blood test screens for the following : pregnancy associated plasma protein-A (PAPP-A) and free ß-human chorionic gonadotrophin (free ß-hCG) • The ultrasound marker is nuchal translucency (NT). (measures the posterior fluid pocket at the back of the foetus’ neck. Increased NT is a sign for down syndrome. • The test can screen for Downs, Edwards and Patau’s • In pregnancies with Down's syndrome, PAPP-A tends to be low, NT and free ß-hCG levels tend to be raised. • If a high risk result is obtained (1 in 150 or higher) for Downs the test will be screen positive. The mother will be offered the option of another follow up test, e.g. NIPT, amniocentesis, or CVB. • If the risk of having a term pregnancy affected with Edwards' syndrome is 1 in 100 or higher you will be offered another ultrasound examination and CVS or amniocentesis. • 6.1% false positive rate • More accurate than the quadruple test The Quadruple Test 1. Screening test 2. 14 - 20 weeks 3. It is a blood test that tests for 4 markers – 1. alpha-fetoprotein (AFP) 2. total human chorionic gonadotrophin (hCG) 3. unconjugated oestriol (uE3) 4. inhibin-A (inhibin) 4. In pregnancies with Down's syndrome, AFP and uE3 levels tend to be low and hCG and inhibin levels tend to be raised. 5. The level of AFP is also used to determine if there is an increased risk of spina bifida or anencephaly. 6. Only screens for down syndrome 7. It is not as accurate as the combined test 8. If the risk of having a term pregnancy affected with Down's syndrome is 1 in 150 or higher the result will be screen-positive and you will be offered an amniocentesis. 9. Has a 6.2% positivity rate. CVS AND AMNIOCINTESIS ARE DIAGNOTIC TESTS NOT SCREENING TESTS AS THEY CAN GIVE A DEFINIATIVE TEST RESULT FOR DOWN’S, PATAU’S AND EDWARD’S SYNDROMES. Chorionic Villus Sampling Amniocentesis • This test is very accurate, and can be • Usually between 10-20 ml of amniotic fluid are taken. performed from around 11 weeks of • Amniotic fluid contains cells with the same genetic makeup pregnancy. as the foetus. They use a small amount to check the genes • The miscarriage risk of this procedure is about and chromosomes of the foetus. 1%. There are also some very rare side effects • This test is very accurate and can be performed at 15 weeks with the invasive procedure such as Cramping, of pregnancy. bleeding, or leaking of amniotic fluid (water • The miscarriage rate for this procedure is 0.5%. The risk is breaking), Infection, preterm labour and Limb higher if the procedure is carried out before 15 weeks. It's defects in infants, especially in CVS procedures not known for certain why amniocentesis can lead to a done before 9 weeks (very rare). miscarriage. But it may be caused by factors such as infection, bleeding or damage to the amniotic sac that surrounds the baby. CVS vs Amniocentesis Chronic villus sampling (CVS) Amniocentesis 1. Difficult to carry out at earlier stages in the pregnancy 1. Club foot - Having amniocentesis early (before week 15 of 2. Miscarriage – higher chances of miscarriage if the test the pregnancy) has been associated with an increased risk procedure is done earlier than 10-11 weeks of the unborn baby developing club foot. Club foot, also 3. Limb abnormalities in the developing baby – a study known as talipes, is a congenital (present at birth) conducted in 90’s showed that some Women had babies deformity of the ankle and foot. Because of the increased that were born with missing fingers and toes and the thing risk of a baby developing club foot, amniocentesis is not they all had in common was that their CVS was carried out recommended before 15 weeks of pregnancy. before 10 weeks. 2. Miscarriage - The rate of miscarriage increases the earlier the amniocentesis is performed. 3. Amniotic fluid levels - Before 15 weeks of pregnancy, the amount of amniotic fluid levels is lower. This makes it more difficult to obtain enough amniotic fluid for testing. NIPT • If a couple receives a high risk result from the combined test they will be offered the NIPT test. • NIPT is a maternal blood test. From this blood sample a lab will analyse small fragments of DNA known as cffDNA – cell free foetal DNA. • cffDNA is DNA released from the placental trophoblasts which circulates in maternal blood and then is isolated separately from maternal blood and tested. • Once tested the results can determine whether the baby has Downs, Edwards or Patau. • NIPT is much more accurate than the combined test - >99% sensitive for Downs and Patau. 91.7% sensitive for Edwards. • The results received from a NIPT test can be: high risk, low risk, or results not obtained. • No results obtained is usually because not enough foetal DNA is present to test. NIPT challenges: • BMI – studies have shown that as the weight of the mother increases, the amount of Foetal fractions of cffDNA in the maternal blood decreases and therefore inaccurate results can be given. • Multiple pregnancies – in the NIPT test the cffDNA obtained would not be able to distinguish between the DNA of each other foetus’ and therefore cannot accurately give results. • Ethical and psychosocial issues – not just a standard blood test. The test is a choice.History Of Abortion Laws Made by Natalja Woloncewicz – Yr 1 Legal Criteria For Abortion In order for an abortion to be legal in the UK it must meet 1 of the 4 following standards/criteria: You will be asked about legal criteria for 1. ‘a pregnancy is terminated by a registered medical abortion 100%. They may give you a scenario and ask if its legal or they may ask practitioner if two registered medical practitioners are of the opinion, formed in good faith’ meaning that a licensed you straight questions about the laws. professional must perform the abortion and two professionals must agree it is for the right reasons and it meets the criteria of the law. • The other sections do not require the baby 2. ‘that the pregnancy has not exceeded its twenty-fourth to be at 28 weeks gestation. week and that the continuance of the pregnancy would • Subsequently amended by the Human involve risk, greater than if the pregnancy were terminated, Fertilisation and Embryology Act 1990 down of injury to the physical or mental health of the pregnant to 24 weeks woman or any existing children of her family; or that the • Must be ‘carried out’ in a licenced termination is necessary to prevent grave permanent injury hospital/clinic to the physical or mental health of the pregnant woman.’ • Allows any practitioner to opt out if they 3. That the continuance of the pregnancy would involve risk conscientiously object (unless the women’s to the life of the pregnant woman, greater than if the life is at risk) cf. students. Medical students pregnancy were terminated must meet GMC guidelines about the 4. That there is a substantial risk that if the child were born it knowledge of the law. they do not have to would suffer from such physical or mental abnormalities as perform abortions. to be seriously handicapped. • Requires certain records to be kept YouTube Videos Down Syndrome • https://www.youtube.com/watch?v=ze_6VWwLtOE&t=3s – fantastic Disorders Arising from Chromosome Abnormalities: it is important to know a at explaining to different mutations which can cause down syndrome few of the symptoms of each disease and then the associated abnormality. Also including non- disjunction, Robertsonian translocation, and mosaic familiarise yourself with the appearance of the disease, as pictures of individuals down syndrome. As well as explaining briefly some of the symptoms can be given and you have to identify their disease. and physical attributes of down syndrome. • Edwards Syndrome - https://www.youtube.com/watch?v=u_gJ34IoUJ8 • https://www.youtube.com/watch?v=dNmcahlZPyM – video by khan • Turners syndrome – https://www.youtube.com/watch?v=YQG8o5b4lKg academy going into more detail about down syndrome. • Klinefelter’s syndrome - https://www.youtube.com/watch?v=71ZyO437w4c • https://www.youtube.com/watch?v=VjerK_JssPs this is a video on the diagnosis of down syndrome. Chronic villus sampling and the criteria of a down syndrome and high risk pregnancy is important. It is a good Screening During Pregnancy (this is a massively important topic – many questions get asked on this) introduction to screening of down syndrome • https://www.youtube.com/watch?v=_afr5olIpTM a basic NHS overview of The Cell Cycle • Meiosis vs Mitosis - https://www.youtube.com/watch?v=IQJ4DBkCnco – screening this Is an A-Level/ GCSE topic but it is good to recap as it can come up • https://www.youtube.com/watch?v=odYHHgzsc_4 – a little bit more in depth. • You need to know about the 10-14 week scan (combined test) – PAPP-A, Nuchal often in exams. Usually as a comparison question or a difference translucency, free B-hCG. Also the quadruple test – 14-20 weeks AFP, hCG, uE3, question. inhibin A. • DNA Replication (S- Phase) https://www.youtube.com/watch?v=eM7arWJJ3zk&t=167s this is a • Chorionic villus sampling - https://www.youtube.com/watch?v=jWZYTbYTycg fantastic video of replication. Need to know about the different you need to know the difference between transabdominal and transvaginal and what it tests for. When can it be done and why can it not be done earlier. enzymes: topoisomerase, DNA ligase, DNA helicase, DNA primase, DNA • Amniocentesis - https://www.youtube.com/watch?v=Ga7nqCk8ao8 and polymerase, RNAase H. also understanding the concepts of leading and https://www.youtube.com/watch?v=bZcGpjyOXt0 the same as CVS, when can lagging strands, origins of replication, consensus areas/origins of it be done, what is it, why can it not be done earlier? replication, Okazaki fragments. • Structure and Function of Chromosomes - • Comparing CVS and Amniocentesis - https://www.youtube.com/watch?v=GB0JkmMhGnQ the exam questions at https://www.youtube.com/watch?v=BbA-pHyirzo this video is a little in the end aren’t that important but if you’re interested it may be good to watch depth however having a basic understanding of the structure and as these may be similar to what you will see on the progress test. function of chromosomes is important. Including centromere, telomeres • NIPT - https://www.youtube.com/watch?v=TnlnLXX2HEE&t=312s and sister chromatids, alleles. YouTube Videos to Watch Karyotyping – you need to be able to identify diseases from a karyotype. Only the ones listed above. Usually an additional or missing chromosome. CASE 2 Anatomy https://www.youtube.com/watch?v=MP3mm04OrQg you • Pelvic Floor - https://www.youtube.com/watch?v=P3BBAMWm2Eo • Pelvic floor 2 - https://www.youtube.com/watch?v=D4Mrytn9Cw0 also need to have an understanding of how scientists create • The perineum - a karyotype and how they order the chromosomes. https://www.youtube.com/watch?v=LTCzTMkYBkU&t=254s Products of Conception - • Need to understand the concept and boundaries and limited https://www.youtube.com/watch?v=0z2RGHI6vGw this is a contents of the urogenital and anal triangle – video also helps with video detailing POC and the process/ uses. It goes into lot amore structured approach to the perineum - https://www.youtube.com/watch?v=mt6jmj6hQWY of detail but you should aim to understand the benefits, what the definition is, why we do it, and what the retained products of conception are.