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49 Cards in this Set

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