MIDTERM 1 Flashcards
1
Q
What are the 4 phases of the eukaryotic cell cycle?
A
G1, S, G2, mitotic phase (mitosis and cytokinesis)
2
Q
What does mitosis do?
A
it generates new cells for growth and repair (makes identical daughter cells)
3
Q
What is cohesion and what is it composed of?
A
it holds sister chromatids together (is put on DNA before replication) – composed of 3 heterotrimer rings (polypeptides)
4
Q
When Cohesin rings are broken, what occurs?
A
anaphase
5
Q
How many chromosomes are in a gamete?
A
n=23
6
Q
What is a genome?
A
all of the genes in a haploid cell
7
Q
What # changes during a cell cycle, chromosomes or DNA?
A
DNA – chromosome #s don’t change
8
Q
Mitosis vs fertilization vs meiosis
A
mitosis: 2n = 2n + 2n
fertilization: n + n = 2n
meiosis: 2n = n + n + n + n
9
Q
What does fertilization do?
A
joins 2 haploid cells into a diploid cell
10
Q
What does meiosis do?
A
to make haploid cells from a diploid cell
11
Q
Protected vs unprotected cohesins
A
pro: holds sister chromatids together
unpro: holds homologous chromosomes together
12
Q
Anaphase 1 vs2
A
1: unprotected cohesins separate chromosomes (l to X)
2: protected cohesins separate into sister chromatics (X to l l)
13
Q
When do homologous chromosomes separate into sister chromatids?
A
going from meiosis 1 to 2
14
Q
What is spermatogenesis?
A
meiosis in males
15
Q
What is oogenesis?
A
meiosis in females
16
Q
What is gametogenesis?
A
meiosis when products are gametes
17
Q
How do haploid cells become motile in spermatogenesis?
A
by growing flagella
18
Q
When do cells begin entering meiosis for spermatogenesis and how long does the process take?
A
at puberty, taking about 2 months (60 days)
19
Q
What is special about oogenesis?
A
it makes a single large haploid cell rather than 4 little ones, the discarded ones being polar bodies
20
Q
What occurs during oogenesis?
A
the cells start meiosis in the fetus and pause in prophase 1
- next, once a month (beginning at puberty), one or two cells resume and enter the oviduct where they would be allowed to be fertilized
21
Q
How many c (chromosomes) do the sperm and egg have?
A
23 each
- egg has a cytoplasm with mitochondria
22
Q
When do genes turn on?
A
in the 4 cell stage (called zygotic genome activation)
23
Q
What do the inner cells of the blastocyst become?
A
embryo
24
Q
What do the outer cells of the blastocyst become?
A
the membrane/placenta
25
What does dizygotic mean?
non identical twins -- independent membranes and placentas in the uterus
26
What does monozygotic mean?
identical twins -- same membranes and placentas in the uterus
27
How are identical/monozygotic twins created?
by splitting at the 2 cell stage
28
What does amniotic fluid contain?
embryonic cells (amniocentesis)
29
What are the sexes for yeasts?
they have mating types (a and alpha)
30
How does yeast get from n to 2n?
normally its through fertilization but with yeasts its through cell fusion
31
What are the sexes for yeasts?
they have mating types (a and alpha) n =16
32
What are corns gametes?
pollen and eggs
33
How do corn pollinate?
they cross pollinate
34
How do corn pollinate?
they cross pollinate (through wind)
35
When does budding occur?
during mitosis when cytokinesis is unequal
36
What are the nucleic acid rules?
1. its made using triphosphate nucleotides
2. made 5' to 3' (direction of synthesis)
3. made using a ssDNA template
4. pair antiparallel
5. pair with complementary base pairing (atu and cg)
37
What happens when an ori fires?
2 replication forks leave at different directions around the circle
38
What are telomeres?
sacrificial pieces of DNA that are the end parts
39
How are telomeres made?
with telomerase (composed of protein and RNA -- not DNA)
- RNA dependent DNA polymerases
40
What creates a nucleosome?
DNA + Histone proteins
- irregular 30nm fibre
41
What is condensin?
large protein complexes that play a central role in chromosome assembly and segregation during mitosis and meiosis
- hold DNA loops
- similar to cohesins but these hold sister chromatids
42
What are metaphase chromosomes made of (x4)?
1. DNA
2. histone proteins
3. cohesin proteins
4. condensin proteins
43
What does metacentric mean?
centromere is located in the middle of the chromosome
44
What does acrocentric mean?
centromere is located towards one side of the chromosome
45
What does telocentric mean?
centromere is located towards one end of the chromosome
46
How many pairs of autosomes vs sex chromosome does a human have?
22 pairs auto, 1 pair sex
47
What "centric" are human chromosomes NOT?
telocentric (one side all the way)
48
How do you prepare chromosomes to be seen?
1. isolate blood
2. add WBC growth factor (increases WBC and you leave it for 3 days)
3. add microtubule inhibitor (culture for 1 day -- chromosomes end up in mitosis)
4. drop cells onto a slide
5. add giemsa stain (causes a metaphase spread and makes cells purple)
6. take a photo and arrange the chromosomes into standard pattern (on a KARYOGRAM)
7. describe the results using the book called ISCN
49
How would you write out a karyotype?
#chromosomes, sex chromosome, abnormalities
ex. 46,XY,+21 (an added chromosome at spot 21)
50
What are the 2 types of chromosome arms?
p arm (small) and q arm (tail)
51
What are each region on a metaphase map called (chromosome)?
a band -- dark and light purple
52
What is the middle of a band called?
a centimere
53
Where are regions located on a band?
from centimere to the end (p and q arm regions)
54
What is the order for naming bands?
chromosome:arm:region:band:sub-band
55
What are the 4 types of chromosome structure changes?
deletion, duplication, inversion and translocation (del, dup, inv, t)
56
What is a gene?
a DNA region responsible for the production of an RNA molecule (mRNA, RNA, etc.)
- work pretty much the same way in prokaryotes and eukaryotes
57
What is a promoter?
located on a gene, where the RNA pol attaches
58
What are regulatory regions?
places where transcription factor proteins attach on a gene
- the regions of a gene where RNA polymerase and other accessory transcription modulator proteins bind and interact to control RNA synthesis
- 10-20bp long
- where the protein can bind
59
What are transcription factors?
positive and negative (ly affect gene activity) -- bind to double stranded DNA
- proteins involved in the process of converting or transcribing DNA into RNA
- attached to the regulatory region
- bind with an amino acid - base hydrogen bonds
- bind instead of open as it takes too much time and E
- bind to several bp to increase specificity and strength
60
What is an environmental gene expression?
when a gene is on only certain environments (controlled by them)
61
What are alleles?
different forms of a gene (a+/A OR a-/a)
62
What is spatial gene expression?
when a gene is on in only some cells
63
What is temporal gene expression?
when a gene is on in only some developmental stages
64
What is a genotype?
all the genes and alleles present in a cell/organism
65
Homozygote vs heterozygote
homo: with identical alleles of a gene of interest (A/A and a/a)
hetero: with different alleles of a gene of interest (A/a)
***doesn't matter if in G1 or G2, treat the same***
66
What are the characteristics of homologous chromosomes?
same: length, centromere position, bands and genes
different: alleles
67
What is a phenotype?
the physical characteristics of a cell/organism
=genotype + environment
68
What is an important detail about hetero chrom?
the dominant allele conceals the recessive allele
69
What is uncertainty (genes)?
if a cell has a dominant phenotype but we don't know if its A/A or A/a (written as A/_)
70
What does a / vs ; mean in nomenclature?
/ = homologous chromosome
; = different chromosome
71
Parental vs recombinant
parental: same as what we started with, the parents
recombinant: new combo from the parents of alleles
72
What is the function of a meiotic crossover?
to hold homologous chromosomes together during meiosis 1
- minor function is to produce recombinant offspring
73
Crossovers can happen between what?
any 2 non sister chromatids
74
What are some examples of minimal media?
carbon or energy source or salts
75
What are some examples of complete media?
AA, sugars, lipids, nucleotides, etc.
76
What is a prototroph?
wild source, genes are all functional and can grow on both CM and MM
77
What is an auxotroph?
lab source, one gene is a mutant and they only grow on CM
78
What is a transfection?
same thing as transformation but in animals (the uptake and use of DNA or RNA by a cell/organism)
79
What is ethyl methanesulphonate (EMS)?
it sticks to G and reacts with damages -- can resemble an A (GC to AT bp sub)
- used to deliberately cause mutations
80
What is ethyl methanesulphonate (EMS)?
it sticks to G and reacts with damages -- can resemble an A (GC to AT bp sub)
- used to deliberately cause mutations
81
What is NHEJ?
bind and sticks to the ends of chromosomes when broken due to gamma or x-rays (telomeres on other ends so they know which sides to put back together - shield them)
82
How do mutagens relate to mutations?
directly related -- mutagen (an agent such as radiation or a chemical substance) makes a lesion which causees dna replication/dna repair to turn it into a mutation (causes genetic mutations)
83
forwards vs reverse mutations
forward: wild type to mutant
reverse: mutant to wild type
84
What are hypomorphic mutations?
affects the protein but not really, decreases the amount or activity of the protein (some)
85
What are amorphic mutations?
causes the protein to be absent or nonfunctional
86
What are genes named by?
by mutant phenotype or protein
87
What are alleles named by?
by discovery or phenotype
88
What is the search tool called for genes and genetic phenotypes?
OMIM online mendelian inheritance in man
89
How many pseudogenes do humans have?
about 12,000
90
What are neutral muitations?
when the protein is unaffected (doesn't matter as much)
91
What are germline mutations?
a gene change in a reproductive cell (egg/sperm) that affects the DNA of every cell in the body of the offspring
92
What are somatic mutations?
an alteration in DNA that occurs after conception (anywhere except germ cells -- don't affect children)
93
What are inherited mutations?
when a gene mutation is carried in the egg or sperm and is passed onto the child (hereditary)
94
What does forensics help find?
DNA differences within a species
95
What is an operon?
a DNA region responsible for making an mRNA with more than one protein coding region
96
What type of mutations does EMS generate?
missense and nonsense
97
What are induced random mutations?
when you expose many organisms to a mutagen to generate random mutations and then isolate the rare offspring with the desired mutant phenotype
98
What are targeted mutaaations?
when you replace the wild type allele of a known gene with a mutant allele (can be done with CRISPR)
99
What are promoters?
a region of DNA upstream of a gene where relevant proteins such as RNA polymerase and transcription factors bind to initiate transcription of that gene (produces an RNA molecule)
100
What is mRNA?
a type of single stranded RNA involved in protein synthesis -- made from DNA during transcription -- carries protein information
