cell division and reproduction Flashcards
(74 cards)
1
Q
what is a somatic cell ?
A
a plant or animal cell that forms the body of the organism; excludes reproductive cells (sperm and egg)
2
Q
what are the 3 functions of reproduction ?
A
- growth of organism
- repair of tissues and organs that have been damaged
- replace dying or dead cells
3
Q
how long does the cell cycle take ?
A
12 to 24 hours
4
Q
where are the shortest living cells in the body found ?
A
the lining of the stomach
5
Q
where are the longest living cells in the body found ?
A
nerve cells i.e. spinal chord, brain
6
Q
when do our brain cells stop growing ?
A
they stop growing when we’re about 20 and die as we age
7
Q
what are the 6 stages of the cell cycle ?
A
- interphase
- prophase
- metaphase
- anaphase
- telophase
- cytokinesis
8
Q
what happens during the stage of interphase ? how much of the cell life is spent in this stage ?
A
- 90-95 % of the cell life is spent in interphase
- the cell does everything except replicate
- it is called the resting stage
- the DNA duplicates at the end of interphase
9
Q
what happens during prophase ?
A
- nuclear membrane disappears
- chromatins shorten and thicken into visible chromosomes
10
Q
what happens during metaphase ?
A
- the chromosomes line up on the equator of the cell, the middle of the cell
11
Q
what happens during anaphase ?
A
- chromosomes split through the centromere into two identical single strands
- migrate to opposite sides, poles
12
Q
what happens during telophase ?
A
- nuclear membrane reappears
- DNA/chromosomes turn back into chromatin
13
Q
what happens during cytokinesis ?
A
- dividing cytoplasm with all organelles
- each cell gets equal amounts of organelles
- animal cell = cleavage furrow, plant cell = cell plate
14
Q
how many pairs of chromosomes are in the nucleus of a cell ?
A
there are 23 pairs (46) chromosomes
15
Q
chromatid =
A
1 half of a double-stranded chromosome
16
Q
chromatin =
A
strand
17
Q
what are homologous chromosomes ?
A
pairs of chromosomes that appear similar, in terms of their length, centromere location and banding pattern when stained with certain dyes
18
Q
are homologous pairs identical ?
A
homologous pairs are not identical; they are alleles
19
Q
what is an allele ? what are alleles represented by ?
A
- different version/ form of the same gene
- alleles are represented by letters
20
Q
what are genes ?
A
sections of DNA that contain genetic information for the inheritance of specific traits
21
Q
what are nucleotides and what are they made of ?
A
made of nitrogen base, sugar and phosphate
they are the smallest unit of measure
22
Q
what is a karyotype ?
A
a photograph of pairs of homologous chromosomes in a cell, the set of chromosomes of an individual
23
Q
how is a karyotype done ?
A
- white blood cells are stopped during metaphase and a picture is taken
- the chromosomes are shortened and thickened during metaphase, which makes them clearly visible
- white blood cells are big and red blood cells do not have a nucleus
- the sample is stained, which produced a banding pattern on the chromosomes
- chromosomes are taken out and matching pairs are found
- they are aligned according to length, centromere location and banding pattern
24
Q
what is a gamete ?
A
a male or female reproductive cell (sex cell)
25
what is a zygote ?
a cell formed by the fusion of two gametes
26
what is fertilization ?
in humans, the joining of male and female haploid gametes, egg and sperm meeting to create a zygote
27
what is a haploid cell ?
a cell that contains half the number of chromosomes as the parent cell
28
what is a diploid cell ?
a cell that contains pairs of homologous chromosomes
29
what is meiosis ?
the cellular process that produces cells containing half the number of chromosomes as the parent cell, genetic diversity is the goal
30
what is synapsis ?
the aligning of homologous chromosomes during prophase 1 in meiosis, synapsis occurs to form tetrads
31
what are the two key outcomes of meiosis ?
1. Genetic reduction: meiosis is a form of cell division that produces daughter cells with half the number of chromosomes as the parent cell
- Creating cells with the haploid number
2. Genetic recombination: the products of meiosis have different combinations of alleles. Genetic recombination gives rise to offspring that are genetically different from one another and their parents. This greatly increases the genetic variation in a population
- “Shuffling the genetic deck”
32
compare mitosis and meiosis
- Mitosis consists of only one set of division phases and produces two identical diploid cells, meiosis has double but are not identical
- Meiosis is important because it results in genetic variation, which allows for genetic diversity within a population
- Mitosis makes 2 daughter cells, diploid, identical
- Meiosis makes 4 daughter cells, haploid, different
- Meiosis involves the reproduction of gametes
33
how is the genetic deck shuffled ?
1. independent/random assortment
| 2. crossing over
34
what is independent/random assortment ?
the creation of gametes that carry different combinations of maternal and paternal chromosomes
35
what is crossing over ?
the exchange of chromosomal segments between a pair of homologous chromosomes, the exchange of genetic material between maternal and paternal chromosomes
36
how many crossovers can occur in a tetrad ?
from none to up to 10 crossovers can occur
37
what is the chance of having a twin ?
1 in a trillion
38
what is the equation for genetic combination ?
(1/2)^23 X (1/2)^23
39
what is the genotype for klinefelter syndrome ?
genotype is XXY
40
what are some characteristics of klinefelter syndrome ?
- high pitched voice
- asexual to female body contours
- breast enlargement
- little facial/body hair
- sterile (low sperm count)
- small amounts of testosterone
- male because there is a Y
- above average height
- overweight
- no evidence that boys with this syndrome are inclined to be homosexual
- common
- males with down syndrome sometimes also have Klinefelter syndrome
- likely to occur in babies of older mothers
41
what is the genotype for Jacobs syndrome ?
XYY
42
what are the characteristics for Jacobs syndrome ?
- “super males”; may have double the testosterone
- taller than average
- facial acne, slender, poorly coordinated
- usually fertile
- live ordinary lives and most are unaware
- extra testosterone makes some angry, violent, abusive (hasn’t been proven)
43
what is the genotype of Turner syndrome ?
X
44
what are some characteristics of Turner syndrome ?
- shorter stature
- webbed neck
- sexually underdeveloped; small, widely spread breasts
- small jaws
- high arched palates
- don’t look very feminine
- turned out elbows
- do not ovulate; ovaries do not develop normally; eggs are destroyed by the age of two
- rare
- when diagnosed early, hormones can be injected
- can be treated with hormones
45
what are characteristics of Triple X ?
```
- genotype is XXX
“super-females”
- usually an inch or two taller
- unusually long legs (stick-like)
- disproportional
- skinny; no hips
- head looks too small for the body
- emotionally immature (sometimes results in being labelled as troublemakers)
- learning difficulties
- more common than Turner syndrome
- occurs more commonly in older women
- fertile
```
46
what are the 4 methods of diagnosing genetic diseases ?
1. pedigree
2. karyotyping
3. blood test
4. DNA probe test
47
what is a pedigree ?
- look for family history of diseases
| - family tree
48
what is a blood test ?
(for particular protein)
- look at the cookie to find out the recipe
- carriers (heterozygous) will often have less of the correct protein (only 1 copy of the gene) or more of a defective protein
- e.g. Tay Sachs carriers= less enzymes that are required to break down lipids
- e.g. PKU babies- blood from heel- high Phenylketonuria
- up until 2008, we only tested for 2 diseases (PKU, thyroid)
- as of 5 years ago, there are 28 tests (last test is Cystic Fibrosis)
- Canada was called the third world of genetic testing (up until 2008)
- NY is 44, Saskatchewan is 29
49
what is a DNA probe test ?
- for some diseases, DNA sequence of defective gene is known
- complementary DNA probe is made
- labeled with radioactive markers
- if a person’s DNA becomes radioactive (probe sticks) they have the defective gene
- sickle cell, Cystic Fibrosis, DMD, Hemophilia, PKU, Huntington’s
50
what is a genome ?
the complete DNA sequence of an organism
51
what are chromosomes ?
tightly coiled microscopic structures made up of mainly DNA, which consists of four different building blocks called bases (A, T, C, G). the four bases are repeated millions of times to form each chromosome
52
how many chromosomes is the entire human genome consisted of ?
23 pairs with one chromosome from each pair coming from each parent
53
do red blood cells contain DNA ?
no
54
who determines the sex of the baby ?
the father because the mother is only capable of making X chromosomes; half of a males sperm is X and half is Y
55
what is a nucleotide and what is it made of ?
smallest measure of DNA
| phosphate, nitrogen base, sugar
56
how many sperm cells are required to fertilize one egg ?
millions
57
spermatogenesis
the process of producing male gametes (sperm) in mammals)
58
oogenesis
the process of producing female gametes (eggs) in mammals
59
what is a gene mutation ?
change in a single gene
60
what is it called when only one nucleotide is changed ?
point mutation
61
what is a chromosomal mutation ?
part of a chromosome (containing several genes) is moved or whole chromosomes stick together
62
what are the 4 gene mutations ?
1. substitution
2. deletion
3. addition
4. duplication
63
what are the 3 chromosomal mutations ?
1. translocation
2. inversion
3. non- disjunction
64
how many different amino acids are there ?
20
65
what is the name of each triplet
codon
66
what are consequences of mutations ?
- you can end up with a non-functional protein
- a protein that makes a toxic substance
- no protein is made, which can be devastating (i.e. the protein that gives the ability to digest food)
67
what is monosomy ?
the loss of a chromosome as a result of non-disjunction (turner syndrome)
68
what is trisomy ?
the gain of an extra chromosome as a result of non-disjunction (down syndrome)
69
what does invasive mean ?
going in the body
70
what are the two prenatal testing procedures ?
1. amniocentesis
| 2. chorionic villus sampling (CVS)
71
how many women get an abortion after finding out their child has down syndrome ?
80-95 % in canada
72
who are offered early testing (amniocentesis)
all pregnant Canadian women
73
what are the risks of miscarriage with amniocentesis ?
1-200 slash 1000
74
what are the risks of miscarriage with chorionic villus sampling ?
1-100 risk
