Midterm 2 Study (Class) Flashcards
Notes from Class (161 cards)
1
Q
What is DNA?
A
Molecule that stores information to make proteins
2
Q
What describes the two strands of DNA?
A
Complementary and antiparallel
3
Q
What is a nucleotide?
A
Monomer of nucleic acids
4
Q
What are the three parts of a nucleotide?
A
sugar, nitrogenous base, phosphate
5
Q
Who were Hershey and Chase?
A
Scientists that showed DNA encodes heredity
6
Q
Who were Watson and Crick?
A
Scientists that determined structure of DNA
7
Q
What did Chargaff discover?
A
Scientist that found base pairing rules of DNA
8
Q
Who used X-ray diffraction to investigate the structure of DNA?
A
Rosalind Franklin and Maurice Wilkins
9
Q
What type of bonding occurs between base pairs in DNA?
A
Hydrogen bonding
10
Q
What is a genome?
A
All of an organism’s genetic material
11
Q
What are chromosomes?
A
Discrete stretches of DNA in eukaryotes
12
Q
What are genes?
A
Functional units of sequence on chromosomes
13
Q
In what direction is DNA read?
A
5’ to 3’
14
Q
What is transcription?
A
DNA -> RNA
15
Q
What is translation?
A
RNA -> Amino Acid
16
Q
What are the primary differences between DNA and RNA?
A
DNA is missing an oxygen, RNA is single stranded
17
Q
Which is more stable, DNA or RNA?
A
DNA
18
Q
What are the bases of DNA?
A
ACGT
19
Q
What are the bases of RNA?
A
ACGU
20
Q
What is RNA polymerase?
A
Enzyme that transcribes RNA from a DNA template
21
Q
In what direction are RNA molecules created?
A
5’ to 3’
22
Q
In what direction is the strand of DNA read by RNA polymerase?
A
3’ to 5’
23
Q
What are the three stages of transcription?
A
initiation, elongation, termination
24
Q
What happens during transcription initiation?
A
RNApol binds DNA at the gene’s promoter; the DNA helix unwinds; RNA synthesis begins
25
What happens during transcription elongation?
DNA threaded through RNApol at Tc'n bubble
26
What happens during transcription termination?
RNApol reaches 'bumps' in terminator region and 'falls off'
27
In which type of cells does RNA processing occur?
Eukaryotic cells
28
What is heterogenous nuclear RNA (hnRNA)?
The RNA produced from transcription, still needs to be processed
29
What are introns?
Section of hnRNA that is unused
30
What are exons?
Section of hnRNA that is used
31
What is splicing?
Process of removing introns from hnRNA
32
What is a codon?
Three-nucleotide sequence on messenger RNA that codes for a single amino acid
33
What are the three types of RNA that interact to synthesize protein?
mRNA, tRNA, rRNA
34
What type of RNA encodes the amino acid sequence?
mRNA
35
What type of RNA carries amino acids to the ribosome?
tRNA
36
What type of RNA combines with proteins to form ribosomes?
rRNA
37
What is an anticodon?
three-base loop on a tRNA molecule that is complementary to one mRNA codon
38
What is the promoter region?
DNA sequence that signals the start of a gene
39
What is a poly A tail?
A sequence of 50-250 adenine nucleotides added onto the 3′ end of a mRNA molecule
40
What is the terminator region?
DNA sequence that signals the end of a gene
41
What is polycistronic mRNA?
Molecules of mRNA that code for multiple proteins
42
What type of RNA do bacteria create?
Polycistronic mRNA
43
What is nuclear export?
When mRNA exits the nucleus
44
What does the term 'degenerate' describe in genetics?
A word that describes the importance of the three letters of a codon
45
What is the start codon?
RNA codon that signals the start of translation
46
What is a stop codon?
RNA codon that signals the end of translation
47
Where does translation occur?
Ribosome
48
What organelle is responsible for protein synthesis?
Rough ER
49
What is the location of lipid synthesis?
Smooth ER
50
Where does protein folding and maturing occur?
Golgi apparatus
51
What are the four stages of translation?
Initiation, elongation, translocation, termination
52
What happens during translation initiation?
Small and large ribosomal subunits bind mRNA; first tRNA also binds
53
What happens during translation elongation?
Ribosome catalyzes the formation of a peptide bond between amino acids in the P and A sites
54
What happens during translation translocation?
Ribosome ratchets over one codon, jettisoning empty tRNA
55
What happens during translation termination?
Elongation ceases once a STOP codon is reached (UAA, UAG, or UGA); release factors bind the ribosome and the complex falls off
56
What are the three parts of RNA processing?
Cap, poly A tail, and removal of introns
57
What are the three sites on a ribosome?
Exit site, Peptidyl site, Amino acyl site
58
What is the exit site?
Site at which tRNA leaves the ribosome
59
What is the peptidyl site?
The ribosomal site that contains the growing protein attached to a tRNA
60
What is the amino acyl site?
Location on ribosome where new tRNA enters ribosome, binds to mRNA
61
What are the repeating steps of translation?
Elongation and translocation
62
What is gene expression?
The flow of information from DNA to synthesized proteins
63
What are the three types of point mutations?
Substitution, insertion, deletion
64
What is nucleotide substitution?
A single base pair in DNA is changed
65
What is a frameshift mutation?
Insertion or deletion that alters the reading frame of a gene
66
What is a protein misfolding disease?
A mutation causes a polypeptide to be unable to fold
67
What is a prion?
A protein folded into an infectious conformation that is the cause of several disorders
68
What are the two necessary functions of cell division?
Growth & development, and reproduction
69
What are gametes?
Cells involved in sexual reproduction; sperm and egg cells
70
What is fertilization?
Process in sexual reproduction in which male and female reproductive cells join to form a new cell
71
What is a zygote?
A diploid cell resulting from the fusion of two haploid gametes
72
What type of cell division does a zygote undergo?
Mitosis
73
What is meiosis?
A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell
74
What is apoptosis?
Programmed cell death
75
What is semi-conservative replication?
DNA replication results in one old strand and one new strand present in each daughter DNA molecule
76
What is the origin of replication?
Site where the replication of a DNA molecule begins
77
What is helicase?
Enzyme that unwinds DNA
78
What is DNA polymerase?
Enzyme that replicates DNA
79
What are ligases?
Enzyme that seals up adjacent DNA molecules
80
What is binary fission?
Type of cell division that occurs in prokaryotic cells / how asexual reproduction occurs
81
How many chromosomes are in prokaryotic cells?
1 Chromosome
82
How many chromosomes are in human body cells?
46 Chromosomes
83
What are histone proteins?
The protein around which DNA wraps
84
What is chromatin?
General term for DNA and histone proteins
85
What is a nucleosome?
DNA coiled around histones
86
What are sister chromatids?
Identical copies of a chromosome joined at the centromere
87
What is a centromere?
Location that two sister chromatids are joined
88
What does diploid mean?
Containing two complete sets of chromosomes, one from each parent
89
What are autosomes?
Any chromosome that is not a sex chromosome
90
What are the female sex chromosomes?
XX
91
What are the male sex chromosomes?
XY
92
What does homologous mean?
Term for the two similar chromosomes from each parent, similar but not identical
93
What are alleles?
Alternative versions of a gene
94
What are the three stages of the cell cycle in eukaryotes?
Interphase, mitosis/meiosis, cytokinesis
95
What are the three stages of interphase?
G1, S, G2
96
What is G1 (Gap 1)?
Stage of interphase in which molecules and structures are built up
97
What is S (Synthesis)?
Stage of interphase in which DNA is replicated
98
What is G2 (Gap 2)?
Stage of interphase in which cell prepares for division
99
What is G0?
A resting phase of the cell cycle in which the cell never divides
100
What is the number of chromosomes in a human after DNA replication?
23x2 = 46
101
What are the five stages of mitosis?
prophase, prometaphase, metaphase, anaphase, telophase
102
What happens during Prophase?
Stage of mitosis when chromosomes condense, nuclear envelope breaks, spindle fibers attach
103
What happens during Prometaphase?
Stage of mitosis when chromosomes move to the center of the cell
104
What happens during Metaphase?
Stage of mitosis when chromosomes line up in center of the cell
105
What happens during Anaphase?
Stage of mitosis in which sister chromatids separate
106
What happens during Telophase?
Stage of mitosis when nuclear envelope forms, chromosomes decondense, cell division starts
107
What is Cytokinesis?
Division of the cytoplasm
108
What is the metaphase plate / spindle equator?
Middle of the cell where the chromosomes line up during metaphase
109
What are somatic cells?
Body cells
110
What does haploid mean?
An organism or cell having only one complete set of chromosomes
111
Are the daughter cells from meiosis genetically identical?
The daughter cells from meiosis are not genetically identical
112
What happens during Prophase I?
Stage of meiosis when crossing over occurs
113
What is crossing over?
Homologous recombination, homologous chromosomes exchange genetic material
114
What happens during Anaphase I?
Stage of meiosis when homologous pairs of chromosomes split up
115
What happens during Anaphase II?
Stage of meiosis when sister chromatids are split up
116
What is Interkinesis?
Cell divides in between Meiosis I and Meiosis II
117
What are the three ways eukaryotic reproduction increases genetic diversity?
crossing over, independent assortment, random fertilization
118
What is ribosomal RNA (rRNA)?
Major component of the organelles (ribosomes) that construct proteins.
119
What is transfer RNA (tRNA)?
"Interpreters" that read the mRNA code; insert amino acids to the growing protein.
120
What is a codon?
Sequence of three nucleotides.
121
What is translation?
The nucleic acid code in a mature mRNA is translated into amino acids to synthesize polypeptides.
122
How is gene expression characterized?
Highly regulated.
123
What are mutations?
Involve substitutions, insertions, or deletions of one or more nucleotides in a DNA molecule.
124
Mutations alter the sequence, but not ___________
the number of nucleotides in a gene.
125
What are frameshift mutations?
Result from the insertion or deletion of bases; can drastically affect mRNA translation.
126
How can mutations affect polypeptides?
Mutations can alter polypeptide folding causing genetic disorders.
127
What is the purpose of cell division?
Essential and produces a continuous supply of replacement cells.
128
What are the two types of cell division?
Meiosis to create unique gametes; mitosis to simply regenerate a cell.
129
What is asexual reproduction?
Genetic material is replicated; cell splits into two, generating genetically identical offspring (i.e., clones).
130
What is sexual reproduction?
Offspring's genetic makeup is derived from two parents; traits are mixed up/recombined so genetically different offspring are produced.
131
What happens during fertilization (mitosis)?
A zygote forms, grows, and divides mitotically or "clones" itself into the trillions of cells in our body.
132
What is the role of DNA polymerase?
Builds new DNA (5' - 3') off of each template strand.
133
What are chromosomes?
Chromatin (DNA + histone proteins); DNA is divided among these.
134
Chromatin is wound up into tight fibers of
nucleosomes
135
When do chromosomes condense?
After replication and only before division.
136
What are sister chromatids?
Condensed replicated chromosomes.
137
How many pairs of autosomes and sex chromosomes do humans have?
22 pairs of autosomes and 1 pair of sex chromosomes (designated X and Y).
138
What is a homologous pair?
They contain the same genes, but may have different alleles or "flavors" of the same gene.
139
What is the cell cycle?
The sequence of events between divisions.
140
What is interphase?
The time between divisions; cell growth and DNA replication.
141
What is mitosis?
Division of the chromosomes; describes what is happening in somatic cells.
142
What are the six arbitrary phases of mitosis?
Prophase, Prometaphase, Metaphase, Anaphase, Telophase, Cytokinesis.
143
What occurs during metaphase?
Chromosomes with spindle fibers attached to their centromeres move to the middle of the cell (the metaphase plate or spindle equator).
144
What happens during anaphase?
Centromeres divide to convert each sister chromatid into a chromosome.
145
What happens during cytokinesis?
Cleavage furrow forms, deepens, and cytoplasm divides to yield two daughter cells.
146
What is meiosis?
In germ cells is the form of cell division that yields gametes (sex cells; e.g., eggs and sperm).
147
What happens during fertilization (meiosis)?
The fusion of gametes (an egg and sperm cell) restores the number of chromosomes back to 23 pairs, 46 total (2n).
148
What occurs in meiosis?
Diploid cells (2n) undergo replication and then two rounds of division yielding haploid (n) gametes.
149
Crossover events occur because of
homologous recombination
150
How do homologous pairs and homologous recombination affect genetic diversity?
Both increase genetic diversity in offspring.
151
How many genetically unique individuals can one couple create?
More than 70 trillion genetically unique individuals.
152
What is polyploidy?
Results in extra chromosomal sets; fatal in humans, important to plant evolution.
153
What are nondisjunction events?
Result in gametes with one extra or missing chromosome, e.g., down syndrome.
154
What does DNA technology refer to?
Broad term meaning the manipulation of DNA & genes for some practical purpose, e.g., medicine, agriculture, forensics, data storage.
155
What are transgenic organisms?
Contain DNA from other species.
156
What are clones?
Genetically identical molecules, cells, or organisms all derived from a single ancestor.
157
What are restriction endonucleases?
Enzymes that cut both strands of the sugar-phosphate backbone of DNA; can cut DNA to leave blunt ends or sticky ends.
158
What are sticky ends?
Have complementary overhangs that spontaneously pair to connect fragments.
159
What are plasmids?
Small self-replicating circular pieces of DNA.
160
What is a ladder in DNA analysis?
Used for comparison to determine the size of the fragments.
161
What is polymerase chain reaction (PCR)?
Can make huge quantities of DNA using automated techniques.
