MCB deck 1 Flashcards
1
Q
how much do human genomic sequences vary by?
A
.1%
2
Q
what is a polymorphism?
A
sequence variant that arose by mutation during human evolution
3
Q
the characteristic predominating in f1 is?
A
dominant
4
Q
how many bp per haploid genome?
A
3.1X10^9
5
Q
how many genes are there in the mitochondrial genome? what are they normally involved in?
A
37 genes involved in ETC and oxidative phosphorylation
6
Q
what do genes that code for proteins have?
A
an open reading frame
7
Q
what is another name for proband
A
propositus
8
Q
how do dominant diseases usually arrive?
A
spontaneous mutation
9
Q
what is an example of incomplete penetrance?
A
the BRCA1 gene for breast caner- its skips generations. it is an all or non measure
10
Q
what is uncommon about the inheritance of sickle cell disease?
A
sickle cell disease is AR but sickle cell trait is dominant
11
Q
what makes a consanguinity?
A
mating of second cousin or closer or anyone related no further than a great great grandparent
12
Q
what are the examples of pseudo dominance?
A
Type O blood, Blue eyes, Sickle cell in Africa, CF in Quebec
13
Q
what Is complementation?
A
mating between individuals with the same phenotype results in offspring without the phenotype
14
Q
what is common with mitochondrial inheritance?
A
reduced penetrance
15
Q
what is the difference between polyploidy and aneuploidy?
A
polyploidy effects all chromosomes equally ex. 3 or 4 copies of the entire genome
aneuploidy changes the number of one or multiple chromosome unequally
16
Q
the numerical abnormalities that are not lethal
A
trisomy 13, 18, 21 and numerical abnormalities of sex chromosomes
17
Q
what is the most common way to get triploidy?
A
2 sperm fertilize one egg- 66%
diploid sperm fertilizes and egg- 24%
diploid egg is fertilized by a sperm- 10%
18
Q
after the G1 phase what is the content number?
A
2c
19
Q
what is the content number after the s phase?
A
4c
20
Q
what is the order of the phases in mitosis
A
interphase, prophase, metaphase, anaphase, cytokinesis/telophase
21
Q
what is the product of mitosis?
A
identical daughter cells
22
Q
what holds chromatids together? and what allows them to separate?
A
cohesion, separase
23
Q
in what phase is the cohesion removed between the chromatid arms?
A
in metaphase the separase degrades the cohesion
24
Q
separation of ____ in M1 and separation of ____ in M2
A
homologs, chromatids
25
in the preparation of a karyotype:
____ stimulates T cell division
____ prevents spindle formation so cells arrest in metaphase
phytohemagglutinin stimulates T cell division
colchicine prevents spindle formation so cells arrest in metaphase
26
what are the Afrocentric chromosomes?
13, 14, 15, 21, 22
27
what is the chromosomal location of : 7q312
chromosome 7, q arm, region 3, band 1, sub-band
28
the nondisjunction where the 2 chromosome from the same parent are different happens in?
Meiosis I
29
The nondisjunction where the 2 chromosomes from the same parent are identical happens in?
meiosis II
30
what is nullosomy?
missing a pair of chromosomes and is always lethal
31
what is the shock gene?
the gene on sex chromosomes that is on the tip pseudo autosomal region that induces height. so someone who is trisomic for sex chromosomes is tall and someone monosomic is short
32
chimeric vs. mosaic
chimeric- emerges from 2 different cell sources, as in 2 different zygotes that together make one embryo
mosaic- began as one zygote, but then diverged after a mutation or division mistake
33
segregation in robertsonian translocation
happens in meiosis 1, a quadrivalent will form instead of a bivalent. alternate segregation will give you balanced, adjacent segregation gives unbalanced
34
what is robertsonian translocatiopn?
translocation between Acrocentric chromosomes (13,14,15,21,22) the p arms are lost- but there is no essential genetic info on the p arms( it is just repetitive DNA) they are balanced
35
what are the possible outcomes of a robertsonian carrier child?
1/2 or 2/6 will be prenatal lethal- trisomy or monogamy
1/3 or 2/6 of being healthy
1/6 or (1/3 of living children) will have Down syndrome
36
what is the most common translocated Down syndrome?
14q21q
2/3 of the cases are de novo mutation
1/3 of the cases are from a balanced parent
37
what is the result of a 21q21q parent?
100% of children will have Down syndrome
38
pericentric vs. paracentric inversion
pericentric- involve the centromere
| paracentric- do not involve the centromere
39
covalent bonds
sharing of electrons between atoms. the strongest type of bond
40
ionic bonds
interactions of ions or molecules possessing full, permanent charge of opposite signs.
41
Van der Waals force
transient induced dipole-dipole interactions
42
what does H bind with in hydrogen bonding?
O, N ,S , FL
43
a positive charge (at ph 7) is?
| a negative charge (at ph 7) is?
-basic, acidic
44
what kind of rxn is peptide bond formation?
dehydration rxn, forming a covalent bond between alpha carboxyl group and alpha amino group. it requires energy to make this bond so it is irreversible
45
what is the suffix for amino acids
yl- example. tyrosylglycylglycylphenyalanyl
46
what is generally involved in the secondary structure of amino acids?
Hydrogen bonding between carbonyl and amide groups in the peptide bond.
47
which amino acids are not usually found in alpha helices?
proline- it destabilizes it
| glycine- it is too flexible
48
how many residues apart are the h bonds in alpha helices?
4
49
What is a beta/reverse turn?
a 180 degree turn in a peptide chain, helps to make compact globular shapes. includes 4 amino acids usually proline and glycine are included. 1 hydrogen bond between peptide bonds 2 residues apart
50
where are super secondary structures (motifs) normal found
the core region of globular proteins
51
which organization of amino acids determines the function of the protein?
Tertiary structure.
| ex. myoglobin carrying heme in the center
52
what is the actin fold?
a cleft between domains for binding and hydrolysis of ATP, first discovered in Actin but now is identified in many app binding proteins
53
what is the difference between orthologs and paralogs?
orthologs- genes in different species, evolved from a common ancestor gene. generally the same function
paralogs- imperfect copies of genes within a species. different but likely related functions
54
what does folding determine in proteins?
Function!! so if 2 proteins have similar folds they have similar function
55
what is size exclusion chromatography/ gel filtration chromatography ?
separation of the basis of size. smaller molecules enter the beads and migrate slower. larger molecules don't enter the beads and can travel quicker.
56
what is chromatography uses for?
It is used to purify the sample!! but it is not use to analyze
57
What is ion exchange chromotography?
separation of the basis of charge. beads are carrying a charge: cation exchanger: negative charge on beads
anion exchanger- positive charge on beads
58
what is affinity chromotography?
separation is based on binding properties. The proteins that bind the ligand are retained on the column
59
what is the gel used in gel electrophoresis?
polyacrylamide for protein
| agarose for DNA/RNA
60
what is SDS- Page?
Sodium Dodecyl Sulfate, a strong ionic detergent. it Denatures the protein and coats protein with negative charge. it is a strong reducing agent that breaks disulfide bonds. You can then use a log graph when you know the migration to figure out the size of the protein
61
What is the PI of amino acids?
PI is the isoelectric point. which is the pH where there is no net charge. all free amino acids have at least 2ionizable groups. the alpha carboxyl and alpha amino groups. then acidic or basic aa will have 3 pkas.
62
What is isoelectric focusing?
separation of proteins on the basis of their isoelectric points. ampholytes in a gel establish a pH gradient in an electric field. proteins will migrate until they reach their PI
63
What is 2D electrophoresis?
proteins are separated through a gel in 2 perpendicular directions using a different basis of separation in each
64
what is the equilibrium constant?
k= Kon/Koff. it is also called the association constant.
65
What is transcriptional regulation?
Epigenetics, controls the compaction or structure of chromatin
66
What is RNA susceptible to?
Alkaline conditions- or to base. Hydroxide with still the H from the hydroxyl group on RNA. DNA won't break apart this way because of the deoxyribose.
67
What bases are methylated in Eukaryotes?
| What bases are methylated in Prokaryotes?
Eukaryotes- Cytosine- methylcytosine
prokaryotes- both methylcytosine and methyladenosine
Only C's followed by G's can be methylated!!!! so 60-90% of CPG is methylated.
Only A's in the sequence GATC can be methylated.
68
Describe inverted repeats in DNA sequences?
aka palindromic repeats, sequences that read the same 5' to 3' on complimentary strands
69
What are DNA palindromes important recognition sequences for?
for restriction endonuclease and some transcription factors.
For restriction enzymes the palindrome is usually not interrupted
for transcription factors, the palindrome is often interrupted by a few bases.
70
What are mirror repeats important for?
they are important for formation of triple stranded DNA also called hoogsteen or H-DNA
71
What are tandem repeats?
Direct repeats or inverted on the same strand. They are often involved in structural abnormalities- due to unequal crossing over in meiosis.
72
How can you denature DNA?
With heat or with high pH.
73
What is the melting temperature of DNA?
The temperature at which 50% of the DNA is denatured.
The Tm is dependent on the number of H bonds it has to break.
-so the longer the DNa strand the higher the Tm
-the more GC content the higher the Tm
74
What is stringency?
the degree to which mismatches are tolerated in a hybridization rxn.
75
What is susceptible to deamination?
All bases with an amino group are prone to deamination, however deamination of cytosines is by far the most common. Cytosine deaminates to Uracil which is not a normal base in DNA so it quickly gets repaired by base excision repair. however if the cytosine is in a CpG and is methylated it will dominate to form a thymine. so there is no mechanism to remove it. the t will be paired with a g. so then mismatch repair will repair it but it will randomly replace either the T or the G- so about half the time a c-g base is stated to a TA base pair
76
What is deamination?
loss of an amino group, usually is a cytosine -> Uracil.
| It is enhanced by Nitrous Acid- used in meat preservative.
77
What is Depurination?
it is the loss of the base from the nucleotide (it is usually a purine) results in a apurinic site.
78
What are mutagen?
| What are Alkylating agents?
Mutagens- physical, chemical, or biological agents that increase the rate of mutations
alkylating agents- add alkyl groups (methyl or ethyl) to bases. HAVE TO KNOW THE EXAMPLE- O6 methlyguanine is the alkylated guanine that can no longer bind to cytosine and instead bonds to thymine.
79
How does Benzoapyrene damage DNA?
by the addition of bulky groups. can also act as an intercalating agent which will distort the double helix. found in cold tar and tobacco smoke.
80
What are intercalating agents and what is an example?
Intercalating agents- flat, planar molecules that slide between the staked bases of the double helix. distort the double helix and increase separation of bases.
example is ETHIDIUM BROMID- the most dangerous chemical to work with
81
describe radiation induced DNA damage?
ionizing radiation generate free radicals that cause DNA double stranded breaks
ex. UV- generate pyrimidine dimers
82
How are Reactive oxygen species made?
they are generated by irradiation and from oxidative phosphorylation in the mitochondria
despite the protective systems these can still damage DNA
83
where are unusual bases usually seen?
in tRNA, ex. Inosine, pseudouridine, etc. Inosine is importnat in the "wobble hypothesis" in tRNA.
