GENETICS Flashcards
(92 cards)
1
Q
What is chromatin?
A
It is strands of DNA
2
Q
List all phases of Mitosis.
A
Interphase (G1, S, G2), Prophase, Metaphase, Anaphase, Telophase, Cytokinesis.
3
Q
Somatic cells are found in __________ and contain _____ chromosomes.
A
The body, 46
4
Q
What are gametes? How many chromosomes do they have?
A
Gametes are sperm or egg cells that have 23 chromosomes in each.
5
Q
What are the strands that attach to the sister chromatid centromeres called?
A
Mitotic spindles
6
Q
What is a diploid cell?
A
It is a cell that has two identical copies of haploid cells.
7
Q
What is the equation for the diploid cells?
A
2n=46
8
Q
Diploid cells have two sets of 23 chromosomes. What are they names of each set?
A
Maternal and paternal.
9
Q
What is a homologous chromosome?
A
Two chromosomes composing a pair that have the same length, centromere, position, and staining pattern.
10
Q
What is an example of a homologous chromosome?
A
homologous chromosomes will have the eye colour gene at an equivalent location.
11
Q
What chromosomes are the sex chromosomes?
A
X and Y
12
Q
What are autosomes? What is the only chromosome that isn’t an autosome?
A
They are other chromosomes that are numbered from 1 to 22. The 23rd chromosome is the X or Y chromosome that isn’t an autosome.
13
Q
Gametes contain a single set of chromosomes. What is this called in terms of the chromosomes?
A
Haploid cell.
14
Q
What is the haploid cell equation?
A
n=23
15
Q
What is the difference between male and female homologous sex chromosomes?
A
Females have a pair of X chromosomes whereas males have one X and one Y chromosome.
16
Q
Where does human life begin? What is it called?
A
When a haploid sperm fuses with a haploid egg. It is called fertilization.
17
Q
When fertilized, what type of cell is a Zygote?
A
It is a diploid cell containing two sets of haploid chromosomes from the maternal and paternal genes.
18
Q
Are gametes produced in the body by the process mitosis?
A
No. Gametes are the only cells in the human body not produced by mitosis.
19
Q
Gametes are specialized cells, where did they develop from?
A
They develop from germ cells in the gonads (ovaries and testes).
20
Q
What is Meiosis?
A
it goes from being a diploid to a haploid
21
Q
Where does meiosis only occur?
A
In the germ cells otherwise known as the gonads (ovaries and testes)
22
Q
What are the two outcomes of meiosis?
A
Genetic Reduction (cell division that reduces half the chromosomes from parent cell) and Genetic Recombination (different alleles amd increases variation).
23
Q
After chromosomes duplicate in interphase they will divide twice to yield…
A
Four haploid daughter cells.
24
Q
What is sister chromatid cohesion?
A
Sister chromatid cohesion is when the sister chromatids are two copies of one chromosome.
25
In interphase, what happens to the cell?
The cell goes through growth and synthesis phase before dividing, it replicates the chromosome which is held together by centromeres.
26
What is the meiosis cycle?
Meiosis has two cycles with four phases in each.
27
Explain what happens in Prophase I.
Synapsis and Crossing over
28
What is synapsis? (Hint: its in prophase I)
It is when the paired homologs are physically connected along their lengths by a zipper-like protein.
29
What is crossing over? (Prophase I)
It is genetic rearrangement between non sister chromatids. It exchanges corresponding segments of DNA molecules.
30
What is chiasmata?
A structure that forms between a pair of homologous chromosomes by crossover recombination and links the homologs during meiosis.
31
What happens in Metaphase I?
The homologous chromosomes are now arranged with one pair facing each pole. They are attached to kinetochore microtubules.
32
What happens in Anaphase I?
Break down of proteins allows homologs separate. The sister chromatid cohesion is still intact and the pole moves the homologs toward the same pole.
33
What happens in Telophase I and cytokinesis?
The microtubules break down, the nuclear membrane reforms, and the chromosomes return to an uncondensed state. The cell then divides into two haploid daughter cells by cytokinesis.
34
What happens in Prophase II?
Spindle forms and chromosomes move toward metaphase plate.
35
What happens in Metaphase II?
Similar to mitosis but the sister chromatids are no longer identical because of crossing over in Meiosis I.
36
What happens in Anaphase II?
The proteins breakdown which allows the chromatids to separate and move towards the poles of as individual chromosomes.
37
What happens in Telophase II and Cytokinesis?
The meiotic division of the parent cell produces four daughter cells each with a haploid set of chromosomes.
38
What is Meiosis I also called?
It is called the reduction division because it halves the number of chromosomes sets per cell. It reduces from a diploid state to a haploid state.
39
What is spermatogenesis?
It is where meiosis takes place in males.
40
Where does spermatogenesis take place?
Meiosis takes place in the male testes.
41
What is the diploid sperm cell called in spermatogenesis?
The diploid cell is called spermatogonium.
42
When does meiosis start occurring in males? How many sperm haploid cells does meiosis create?
Puberty and during puberty the sperm cell undergoing meiosis will create 4 haploid sperm cells.
43
In sperm where is the nucleus and other important molecules found?
The head of the sperm holds the nucleus and other molecules.
44
What is oogenesis?
It is when meiosis takes place in the female body.
45
What is the diploid cell called in oogenesis?
The oogonium.
46
When does meiosis start occurring in females, and what does the process yield?
Meiosis in females takes place before birth, they go through meiosis and creates an unequal division of cytoplasm.
47
What happens to the unequal division of cells in oogenesis?
Which ever cell that has the most cytoplasm will continue through meiosis I and II.
48
When does the process of meiosis end in females?
It ends once the viable egg is fertilized by the sperm.
49
How does fertilization of a viable egg occur?
Once the egg is mature, the eggs nucleus will fuse with the sperms nucleus to yield a diploid zygote.
50
Can gametes that have errors survive and be fertilized?
Yes.
51
What are the 4 errors that occur to chromosome STRUCTURE.
Deletion, duplication, inversion, translocation.
52
Explain the error called Deletion. Provide its example and which chromosome it affects.
It is when a piece of chromosome is deleted. The result is Cri du Chat syndrome. It happens by deletion in chromosome 5.
53
Explain the error called Duplication. Provide its example and which chromosome it affects.
It is when a section of the chromosome appears two or more times in a row. The result is Charcot-Marie-Tooth Disease, this happens when chromosome 17 duplicates.
54
Explain the error Inversion. Provide its example and which chromosome it affects.
It is when a section of the chromosome is inverted. The result is FG Syndrome, this happens in a section of the X chromosome. This syndrome occurs mostly in males.
55
Explain the error Translocation. Provide its example and which chromosome it affects.
It is when a segment of one chromosome breaks off and attaches to a different chromosome. The result is Chronic Myelogenous Leukemia (CML). It occurs between the chromosomes 9 and 22.
56
What are the symptoms of Cri du Chat syndrome? Which chromosome does it occur from?
Symptoms: high-pitched cat-like cry, low birth weight, widely spaced eyes, recessed chin, and cognitive delays. It occurs in chromosome 5.
57
What are the symptoms of Charcot-Marie-Tooth Disease? Which chromosome does it occur from?
Symptoms: muscle weakness, loss of sensation in hands feet and lower legs, and a high foot arch with constantly flexed toes. It occurs from chromosome 17.
58
What are the symptoms of FG Syndrome? Which chromosome does it occur from?
Symptoms: intellectual disabilities, delayed motor development, low muscle tone, and broad toes and thumps. This occurs in the X chromosome (males)
59
What are the symptoms of Chronic Myelogenous Leukemia?
Symptoms: cancer of white blood cells. Occurs in chromosomes 9 - 22.
60
What are the errors caused by changes in chromosome NUMBER?
Non-disjunction, Trisomies, and Monosomies
61
Define non-disjunction.
It is the failure of the homologous chromosome pairs or sister chromatids to separate during Meiosis. This occurs in Anaphase I or II.
62
What happens with non-disjunction in anaphase I?
During anaphase I it occurs when homologous chromosome pairs do not separate to the opposite poles. One pair of is pulled to the same pole.
63
What happens with non-disjunction in anaphase II?
During anaphase II it occurs when the sister chromatids do not separate again to the opposite poles. The result is too few or too many chromosomes.
64
Explain what is going on in this image.
In A it goes through non-disjunction producing 1 gamete with one extra chromosome leaving the other gamete with zero. During meiosis II it produces too many chromosomes in the 2 gametes leaving the other two with no chromosomes.
In B it goes through correct anaphase I however the gametes produced had one normal anapahse II and one non-disjunction.
65
For A, what would happen if the sperm fussed with one of the gametes with two chromosomes? What would happen with the empty chromosome?
If a sperm gamete fused with the egg gamete with 2 chromosomes the zygote, if successful will have 3 chromosomes.
If a sperm gamete fused with the egg gamete that had no chromosomes the result would be the zygote having only 1 chromosome.
66
Define Trisomy
It is the gaining of an extra chromosome (3 in total) as a result of non-disjunction.
67
Define Monosomy
The loss of a chromosome (1 in total) as a result of non-disjunction.
68
What is Patau syndrome?
It is a trisomy in chromosome 13. It causes intellectual/physical disabilities, organ defects, cleft palates, and early death.
69
What is Edward syndrome?
It is a trisomy in chromosome 18. It causes intellectual/physical disabilities, facial abnormalities, extreme muscle tone, clubbed foot, early death.
70
What is Down syndrome?
It is a trisomy in chromosome 21. It causes intellectual/physical disabilities, abnormal palm creases, almond shaped eyes, flattened face, short stature.
71
What is Klinefelter syndrome?
It is an extra X chromosome in males (XXY). It causes sexual immaturity, breast swelling, feminized physique.
72
What is Jacobs syndrome?
It is an extra Y chromosome in males (XYY). It causes no unusual symptoms, some may be taller than average, reading and speech underdevelopment, and aggressiveness.
73
What is the Triple X syndrome?
It is an extra X chromosome in females (XXX). It causes menstrual irregularity, aggressiveness, delayed motor skills. Goes unnoticed.
74
What is Turner syndrome?
It is when there is only one X chromosome in females (X0). It causes short stature, webbed neck, sexual underdevelopment, facial hair, and infertility.
75
Who was Gregor Mendel?
Mendel was an Austrian monk that studied math and botany. He is known as the father of genetics.
76
Why did Mendel choose the pea plant for his study?
He used because they were readily accessible, had many traits, easy to grow, and they were naturally self pollinating.
77
Define heterozygous.
Carries two different alleles at the same locus on the gene.
78
Define homozygous.
Carries two identical alleles at the same locus on the gene.
79
Define the law of independent assortment.
How genes independently separate when the reproductive cells develop.
80
Define independent dominance.
It is when neither allele is dominant to each other but instead F1 hybrids are a blend of the two parental traits.
81
Explain complete dominance.
F1 hybrids will always look like one parent. One trait will always be dominant or recessive.
82
Explain co-dominance.
Both alleles are fully expressed and dominant.
83
What are the four blood types? (No negatives or positives).
Type: A, B, AB, O
84
Define sex-linked gene.
A gene located on either sex chromosome.
85
Why are there few disorders that fathers can pass onto their sons?
The Y chromosome can only be passed on to male offspring. With fewer than 100 genes on the Y chromosome it isn’t as common for males to inherit any disorders from their father.
86
Can fathers pass their X-linked alleles to their daughters and their sons?
No, only daughters inherit the alleles from their fathers X chromosome.
87
Can mothers pass their X-linked alleles to both daughter and son?
Yes.
88
If a father has a disorder and it is X-linked and dominant, what is the chance the father will pass this disorder on to his daughter?
100% this is because it is dominant and because the daughter will receive the mothers and fathers X chromosome.
89
If a male receives a recessive allele from his mother, will he express this trait?
Yes he will because if the mother passes on the recessive X and the father passes on the Y, then he will express the X.
90
What is hemophilia?
Blood clotting disorder.
91
If a male suffers from hemophilia, who did he inherit it from?
His mother because hemophilia is a X-linked disorder and males can only receive X genes from mother.
92
If a man suffers from hemophilia, what is the percentage in which his son might carry the trait?
0% because disorder is X linked.
