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33 Cards in this Set
- Front
- Back
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What is a genome? |
A genome is an organism's complete set of DNA. |
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What is chromatin? |
Chromatin is DNA + RNA + Protein. It is highly condensed in the cell's nucleus. |
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What is a gamete? |
A gamete is a reproductive cell. It fuses with another gamete during fertilization. Female: ova; Male: sperm Gametes are haploid. (see haploid card) |
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What is a zygote? |
A zygote is the initial cell formed by two gametes, or a fertilized ovum. It is diploid. (see diploid card) |
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What is a diploid cell? |
A diploid cell has two sets (2n) of each chromosome, for a total of 23 pairs of chromosomes - 46 chromosomes altogether. The somatic cells(body cells) are all diploid, except for red blood cells. |
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What is a haploid cell? |
A haploid cell has only one set(n) of unpaired chromosomes, such as found in the ova and sperm reproductive cells. There are a total of 23 chromosomes in a haploid cell. |
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What is mitosis? |
Mitosis produces two daughter cells that are identical to the parent cell.Diploid cells reproduce by mitosis. (Start with one and end with two identical copies) |
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What is meiosis? |
Meiosis is a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. (That's four cells with half the chromosomes as the parent) |
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What cells reproduce by mitosis? |
Diploid cells reproduce by mitosis. |
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What cells reproduce by meiosis? |
Haploid cells reproduce by meiosis. |
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What is the purpose of mitosis? |
The identical daughter-cells produced during mitosis are used to grow and repair damaged tissue. |
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What is the purpose of meiosis? |
There are two main functions: -To reduce the chromosome number in the sperm or egg to 23 (so that when they unite during reproduction there will be 46 again) -To ensure that every sperm/egg is genetically unique. |
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What is crossing-over? |
Crossing-over occurs during the first phase of meiosis. (not mitosis) It is the exchange of genetic material between non-sister chromatids. (Think of it as the great DNA shuffle!) |
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What are the causes of chromosomal disorders? |
There are four causes of chromosomal disorders: 1) Increasing maternal age 2) Ionizing radiation 3) Chemical/Drugs during pregnancy 4) Idiopathic (of unknown cause) |
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What is aneuploidy? |
It is an abnormal chromosome number in which the chromosome number is not a multiple of 23 (which is the normal haploid number for humans). There is a loss or gain of 1 or 2 chromosomes. It is caused by non-disjunction. (see cards on non-disjunction) |
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What is non-disjunction? |
Nondisjunction is the failure of chromosomes to separate during mitosis or meiosis. |
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What are the two types of non-disjunction? |
1. Monosomy - loss of chromosome (causes abnormal zygote and often death of fetus) 2. Trisomy - Gain of chromosome |
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What is Trisomy 21 and its characteristics? |
"Down's Syndrome." It results from an extra chromosome(total of 3) on Chromosome 21 due to non-disjunction (see card on nondisjunction) Those with this condition have wide-spaced eyes; small, low-set ears; large forehead; broad nasal bridge. They also suffer from congenital heart disease, morphologic brain changes similar to Alzheimer, and increased susceptibility to infection. |
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What is polyploidy? |
This is an even more serious abnormality of chromosome number, usually resulting in spontaneous abortion. The chromosome number is greater than 2 times the haploid number. Triploid is 3 times the haploid number (26x3) Tetraploid is 4 times the haploid number (26x4) |
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What is deletion? |
Absence of full or partial chromosomes. |
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What do "p" and "q" mean in chromosomal scientific notation? |
"P" is the short arm of the chromosome. "Q" is the long arm of the chromosome. |
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What is inversion? |
Inversion is the reunion of a previously broken chromosome - but the fragments are re-inserted in an inverted (upside-down) position! |
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What is translocation? |
Translocation is the rearrangement of parts with the exchanges of chromosomal segments between nonhomologous chromosomes (an unpaired chromosome) There is no loss of genetic material - often clinically silent. |
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In summary, what are the five types of abnormal chromosomal number and/or structure? |
1. Aneuploidy 2. Polyploidy 3. Deletion 4. Inversion 5. Translocation |
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What is an autosomal chromosome? |
It is one of the first 22 chromosomes (the somatic chromosomes) - all except the sex chromosomes. |
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What is three autosomal chromosomal disorders? |
Down Syndrome (Trisomy 21) Edwards Syndrome (Trisomy 18) DiGeorge Syndrome (Microdeletion of chromosome #22q) |
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Describe Edwards Syndrome |
This syndrome results from meiotic translocation.(see card on translocation). It is due to an extra chromosome on chromosome #18. Characteristics include: Rocker-bottom feet, prominent occiput, small jaw, and claw-shaped fingers. |
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Describe DiGeorge Syndrome. |
It is due to microdeletion of chromosome #22q. (see card on deletion) Sometimes called "CATCH 22" as a memory-aid: C-ardiac abnormalities A-bnormal facial expression T - cell deficit (from thymus hypoplasia0 C - left palate H- ypocalcemia (abnormally low levels of calcium in the body) |
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What are two sex chromosome conditions? |
Klinefelter Syndrome (XXY) Turner Syndrome (X) |
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Describe physical characteristics of Turner Syndrome (X)? |
-Short stature -Swelling -Broad chest -Low hairline, low-set ears -Ear infection and lost hearing -Webbed necks (My own memory aid, using the first letter of each word: Some Say Birds Like Eating Worms:-) |
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Describe physical characteristics of Klinefelter Syndrome(XXY) |
-Weak muscle -Strength decreased -Testosterone decreased -Facial hair decreased -Pelvis wider -Breast tissue increased (My own memory aid,using the first letter of each word: Worms Seem To Feed Pecking Birds:-) |
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What is a teratogen? (IMPORTANT: Know How To Spell It!) |
Teratogens cause fetal abnormalities (under 8 weeks of development) They can be viral, chemical, or physical. |
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What is a centromere? |
A centromere is the part of the chromosome that links sister chromatids. |
