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MCAT Biology > Genes > Flashcards

Genes Flashcards

(105 cards)

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1
Q

eukaryotes have ___ of some genes, while prokaryotes have ____ of each gene

A

eukaryotes have more than one copy of some genes, prokaryotes have only one copy of each gene

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2
Q

The Central Dogma

A

DNA –> RNA –> protein

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3
Q

DNA nucleotides differ from each other only in their…

A

nitrogenous base

adenine, guanine, cytosine, thymine

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4
Q

purines

A

2 ring structures, adenine and guanine

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5
Q

pyrimidines

A

1 ring structures, cytosine and thymine

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6
Q

DNA directionality

A

5’ –> 3’

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7
Q

DNA replication is ____

A

semiconservative: when a new double strand is created, it contains one strand from the original DNA, and one newly synthesized strand
semidiscontinuous: one strand is continuous, one fragmented

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8
Q

bidirectional replication process

A

from the origin, two replisomes proceed in opposite directions along the chromosome

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9
Q

DNA polymerase

A

builds new DNA strand, can only add nucleotides to an existing strand

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10
Q

primer

A

RNA primer approx. 10 ribonucleotides long to initiate the strand

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11
Q

DNA ligase

A

connects Okazaki fragments on lagging strand

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12
Q

telomeres

A

end of eukaryotic chromosomal DNA, protect chromosomes from being eroded through repeated rounds of replication

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13
Q

differences of RNA

A

carbon 2 on the pentose is not deoxygenated
RNA is single stranded
RNA contains the pyrimidine uracil instead of thymine

can move through the nuclear pores

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14
Q

mRNA

A

delivers the DNA code for amino acids to the cytosol where the proteins are manufactured

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15
Q

rRNA

A

combines with proteins to form ribosomes, direct synthesis of proteins
synthesized in the nucleolus

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16
Q

tRNA

A

collects amino acids in the cytosol, transfers them to the ribosome for incorporation into the protein

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17
Q

2 places where eukaryotic transcription can take place

A

nucleus and mitochondrial matrix

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18
Q

promoter

A

sequence of DNA that designates a beginning point for transcription

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19
Q

activators and repressors

A

bind to DNA close to the promoter, activate or repress the activity of RNA polymerase
allosterically regulated by small molecules (cAMP)

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20
Q

operon

A

prokaryotic, genetic units that consists of the operator, promoter, and genes that contribute to a single prokaryotic mRNA

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21
Q

post transcriptional modification occurs _____ for eukaryotes

A

in the nucleus

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22
Q

primary transcript

A

initial mRNA nucleotide sequence from transcription

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23
Q

post transcriptional processing at ends

A

5’ cap: attachment site for protein synthesis, protects against exonucleases
Poly A tail: protects against exonucleases

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24
Q

introns remain in the ____

A

nucleus

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25
snRNPs
small nuclear ribonucleoproteins | recognize sequences at end of introns
26
denatured DNA
2 strands of double helix are separated
27
nucleic acid hybridization
separated strands spontaneously associate with their original partner or any other complementary nucleotide sequence DNA-DNA, DNA-RNA, RNA-RNA
28
Restriction enzymes
digest nucleic acid only at certain nucleotide sequences | bacteria use them to cut viral DNA
29
palindromic sequence
rads the same backwards and forwards | restriction sites are palindromic
30
recombinant DNA
artificially recombined DNA | 2 DNA fragments cleaved by the same endonuclease can be joined together regardless of origin of DNA
31
vector
used to insert recombinant DNA into a bacterium
32
plasmid
common vector
33
probe
radioactively labeled complementary sequence of the desired DNA fragment used to search the clone library for the desired DNA sequence
34
complementary DNA / cDNA
when the mRNA produced by the DNA is reverse transcribed using reverse transcriptase, to clone DNA with no introns
35
polymerase chain reaction (PCR)
fast way to clone/amplify DNA
36
anneal
when PCR cools, primers hybridize to their complementary ends of the DNA strands
37
Southern blotting
to identify target fragments of known DNA sequence in a large population of DNA, uses nucleic acid hybridization
38
Northern blot
identifies RNA fragments, just like southern blot
39
Western blot
detects a protein with antibodies
40
RFLP
identifies individuals as opposed to specific genes
41
genetic code
translates the DNA nucleotide sequence into an amino acid sequence and protein
42
genetic code is degenerative
more than one series of 3 nucleotides may code for any amino acid
43
genetic code is unambiguous
any single series of 3 nucleotides will code for only 1 amino acid
44
the genetic code is almost universal
nearly every living organism uses the same code
45
start codon
AUG
46
stop codons
UAA, UAG, UGA
47
probabilities: 4 possible nucleotides placed at 3 possible positions...
4^3 = 64
48
translation
process of protein synthesis directed by mRNA
49
anticodon
set of nucleoitides that is complementary to the codon | from tRNA
50
tRNA
contains the anticodon | sequesters the amino acid that corresponds to its anticodon
51
nucleolus
special organelle where ribosomes are made, eukaryotic
52
P site
peptidyl site, where methionine is put by tRNA
53
initiation complex for translation
after methionine at P site, large subunit of the ribosome joins
54
A site
aminoacyl site, when elongation beings a tRNA with its amino acid attached to the A site
55
transloction
elongation step, ribosome shifts 3 nucleotides along the mRNA toward 3' end
56
E site
tRNA that carried methionie moves here and exits ribosome
57
post-translational modifications
sugars, lipids, and phosphate groups can be added to aa's
58
signal peptide
a 20 aa sequence near front of polypeptide, recognized by protein-RNA signal-recognition particle (SRP)
59
signal-recognition particle
recognized signal peptide, carries entire ribosome complex to receptor protein on ER
60
mutagens
physical or chemical agents that increases the frequency of mutation above the frequency of spontaneous mutation
61
frameshift mutation
from insertion or deletion of a base pair occurs in multiple other than 3
62
missense mutation
base-pair mutation that occurs in the amino acid coding sequence of a gene
63
nonsense mutation
base pair substitution, insertion, or deletion results in a stop codon
64
translocation
when a segment of DNA from one chromosome is exchanged for a segment of DNA on another, caused by transposition
65
inversion
orientation of a section of DNA is reversed on a chromosome, caused by transposition
66
transposable elements/transposons
excise themselves from a chromosome, reinsert at another location
67
forward and backward mutation
forward: change the organism even more backward: revert the organism back to its original state
68
wild type
original state or organism before mutation
69
oncogenes
genes that cause cancer, converted from proto-oncogenes by carcinogens
70
histones
proteins that DNA is wrapped around in nucleus
71
nucleosome
8 histones wrapped in DNA
72
chromatin
entire DNA/protein complex
73
____ chromosomes in nucleus of human cell
46
74
___ homologous pairs of chromosomes
23, traits are the same but actual genes may be different
75
diploid
any cell that contains homologous pairs
76
haploid
any cell that does not contain homologous pairs
77
interphase
G1 (first growth phase), S (synthesis), G2 (second growth phase)
78
G0 phase
nongrowing state distinct from interphase | allows for differences in length of cell cycle
79
during syntheis phase, each chromosome is made of two identical ___ _____
sister chromatids
80
mitosis
nuclear division without genetic change, results in genetically identical daughter cells prophase, metaphase, anaphase, telophase
81
prophase
condensation of chromatin into chromosomes
82
centrioles in centrioles move...
move to opposite ends of cell in prophase
83
____ ____ begins to form during prophase
spindle apparatus
84
aster
microtubules radiating from the centrioles
85
centromere
center of chromosomes
86
___ ___ connect the centrioles during prophase
spindle microtubules
87
kinetochore
structure of protein and DNA at the centromere of the joined chromatids of each chromosome
88
metaphase
chromosomes align along the equator of the cell
89
anaphase
sister chromatids split apart at centromeres, move towards opposite ends of cell
90
cytokinesis
actual separation of the cellular cytoplams due to constriction of microfilaments about the center of the cell
91
telophase
nuclear membrane reform followed by reformation of nucleus, chromosomes decondense, cytokinesis continues
92
Meiosis
double nuclear division that produces 4 haploid gametes/germ cells 2 rounds, genetic recombination occurs
93
spermatogonium and oogonium
undergo meiosis
94
primary spermatocyte or oocyte
after replication occurs in the S phase of interphase
95
meiosis prophase I
homologous chromosomes line up, crossing over can occur --> genetic recombination
96
tetrads
each duplicated chromosome in prophase I looks like an X, side by side homologues exhibit a total of 4 chromatids
97
chiasma
x shape, of 2 attached chromosoes
98
meiosis metaphase I
homologues remain attached, move to metaphase plate, tetrads align
99
meiosis anaphase I
separate homologues from their partners
100
meiosis telaphase I
--> secondary spermatocyes/oocytes
101
polar body
in females, one of the oocytes, much smaller, degenerates | after telaphase I
102
reduction division
meiosis
103
___ appears much like mitosis
meiosis II
104
final products of meiosis II
haploid gametes each with 23 chromosomes | 4 sperm cell, or single ovum
105
nondisjunction
during anaphase I or II the centromere of any chromosome does not split

MCAT Biology (9 decks)

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