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49 Cards in this Set
- Front
- Back
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How is DNA wound up?
Why? |
By uising porties as spools, and scaffolding as supercoiled loops of DNA
If DNA wasn't wound up it would get all tangled and be very difficult to copy |
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When is DNA fully wound up and when is it not?
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Wound up- most of the time
Unwound- during DNA replication and transcription (just before cell divides) |
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When are there 2 DNA per chromosome?
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In all cells but egg and sperm- one one DNA- 23 unpaired chromosomes
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Why are there 2 DNA per chromosome?
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one from mom and one from dad
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What is diploid?
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2n- each chromosome is represented twice as a member of a pair
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What is haploid?
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n- each chromosome is represented once in an unpaired condition
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What's the difference between autosomes and sex chromosomes?
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Autosomes are chromosomes 1-22 that are not sex chromosomes (23- XX for female and XY for male)
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How many chromosomes are in human somatic (body) cells?
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23 pairs and 46 chromosomes
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Which human cells contain one haploid set of chromosomes?
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eggs and sperm
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What is the difference between homologous chromosomes an sister chromatids?
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Each chromotid carries identical genetic information and is joined by a centromere. Homologous chromosomes are chromosomes that pair during mieosis- are not identical but from the same chromosome family.
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When are chromosomes in X's and when are they not?
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??????
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What is a centromere?
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Region of chromosome where two chromatids are attached.
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What are chromosome arms? And what are they're abbreviations?
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The short and long end. The short end p and the long end q.
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How are banding patterns on chromosomes used by scientists?
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????
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Where and when does mitosis occur?
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Anywhere, whenever a cell needs to divide (replace other cells/when space is available)
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Where and when does meiosis occur?
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Occurs in germline cells- only for eggs and sperm
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What are stem cells?
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Undifferentiated cells- used to cure incurable diseases
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Where can stem cells come from?
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Embryo, unfertilized eggs, aobrtions(early embryo), adult body bone marrow, unbilical cord
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What conditions can stem cells treat?
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brain and spinal cord injuries
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What are the roles of the genes that control the cell cycle?
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To figure out when cells need to divide, if they have enough space, and if they are ready to divide
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What is the connection between genes and cancer?
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Genes divide in a controlled manner, unlike cancer. Cancer is immortal and genes are mortal. Gene telemeres get shorter, cancerous get longer. Genes stay put while cancer cells roam through the body.
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What is a benign tumor?
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Tumor that doesn't spread
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Why are no two eggs or sperm alike?
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Cross over
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What is the procedure for karyotyping and what are they looking for?
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Picture of all the chromosomes from one cell arranged in pairs- gotten by blood sample (white blood cells), amniocentisis, or chorionic villus sampling
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What is the procedure for amniocentisis and what are they looking for?
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Sample of fluid around fetus. Used in diagnosing fetalgenetic and developmental disorders
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What is the procedure for chorionic villus sampling and what are they looking for?
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sampling fetal chorionic cells by insertinga catheter through the vagina or abdominal wall into uterus- used in diagnosing biochemical and cytogenetic defects in embryo
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What would the karyotype look like for polyploidy?
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Too many whole sets- 3n rather than 2n
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What would the karyotype look like for aneuploidies?
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set has extra or missing chromosome
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What would the karyotype look like for aneuploidies?
Missing sex chromosome: |
45X or 45Y
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What would the karyotype look like for aneuploidies?
Extra sex chromosome: |
47XXY, 47xyy, 47xxx
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What would the karyotype look like for deletions?
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piece of chromatid is missing
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What would the karyotype look like for translocations?
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piece of one chromosome is attached to another non-homologous chromosome
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What is trisomy and triploidy?
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Trisomy- condition where one chromosome is present in three copies
Triploidy- having three copies of all autosomes and three sex chromosomes |
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What are the effects of having extra autosomes?
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Usually lethal to embryo
3 can lead to live birth: 18- Edwards 13- Patau 21- Down Syndrome -- allows growth in adult hood |
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What are the effects of having missing autosomes?
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always lethal to embryo- causes a miscarriage
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What are the effects of having extra sex chromosomes?
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47xxy- Klienfelter syndrome: sterile males, able to function
47xyy- normal, maybe sterile 47xxx- maybe sterile, female |
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What are the effects of having missing sex chromosomes?
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45x- Turner- web neck stout, shorter, sterile females
45y- lethal to embryo |
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What are the effects of polyploidy?
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always lethal- usually ends in a miscarriage
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What genetic condition is caused by deletions?
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Cri-du-chat Syndrome
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What genetic condition is caused by translocations?
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Down syndrome
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How are the age of the mother nad aneuploidy connected?
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Risk increases with age
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How are chromosome abnormalties and miscarriages linked?
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If the abnormalty is too great, a miscarriage will occur.
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How is sex determined in humans?
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In chromosomes (xx-female, xy-male); determined by the SRY in teh Y or TDF (which determines testes)-- control a protein that will turn on other genes in gonads which cause differentiation into testes
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How do XY females occur?
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SRY switch did not turn on = mutated sterile, no menstral cycle or testosterone
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How do XX males occur?
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translocated SRY gene onto an X- Klinefelter's syndrome; adrenal glands overproduce testosterone
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What are Barr bodies?
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inactivated X-chromosome
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What are the methods of testing sex and how reliable are they?
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PGD- 100%- expensive
Sperm Sorting- 70-90%; cheaper |
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What is the purpose of sex selection?
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to pick the sex of the baby
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What isthe general method of sex selection?
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50-50 chance with chromosomes
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