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Biol 1201 > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

What is the structure of DNA?

A

Pentose Sugar, Phosphate group, Nitrogenous Base (A, T,C, or G)

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2
Q

What are the four possible nitrogenous bases in DNA?

A

Adenine, Thymine, Cytosine, Guanine

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3
Q

What connects nucleotides in a strand?

A

Sugar-Phosphate backbone (Phosphodiester bond)

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4
Q

How are nucleotides read?

A

P to S… 5’ to 3’

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5
Q

How are the nitrogenous bases bonded to each other in DNA helices?

A

Hydrogen Bonds

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6
Q

How many hydrogen bonds does it take to bond Adenine with Thymine?

A

2

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7
Q

How many hydrogen bonds does it take to bond Cytosine with Guanine?

A

3

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8
Q

What is Chargaff’s Rule?

A

A-T, C-G

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9
Q

Used other people’s data and are accredited for realizing DNA is a double stranded helix

A

Watson and Crick

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10
Q

What did Watson and Crick discover about DNA?

A

DNA is a double helix of two nucleotide strands and is held together by complementary base pairs. The complementary strands run in opposite directions

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11
Q

What are the phases of the Eukaryotic Cell Cycle?

A

G1 cell growth and differentiation, S synthesis of DNA and replication of chromosomes, G2 cell growth

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12
Q

What is interphase?

A

The G1, S, G2, and G0 phases of the eukaryotic cell cycle

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13
Q

What is G0?

A

Phase in the eukaryotic cell cycle when matured cells are still active but have stopped growing.

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14
Q

What are the three steps of DNA replication?

A
  1. Separation of parental DNA helix which exposes nucleotide bases.
  2. Incorporation of complimentary nucleotides using DNA Polymerase.
  3. The mother DNA helix produces two daughter helices which each have 1 old strand and 1 new strand
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15
Q

What is the semiconservative Replication Model?

A

states that when the mother chromosome divides into two daughter chromosomes, each daughter chromosome has one new and one old strand. Both strands of original DNA serve as templates

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16
Q

What is a replication bubble?

A

The part of the DNA where the nucleotide bases are exposed and where DNA replication is taking place and continues along the strand in opposite directions

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17
Q

What is the difference between the two strands of DNA being replicated?

A

One is replicated as a continuous segment which allows DNA Polymerase to only put down new nucleotides in the P to S direction.
The other is a segmented (Okazaki fragments).

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18
Q

How is DNA replicated in Okazak Fragments?

A

Polymerase has to wait until enough of the template is exposed to put down segmented nucleotides P to S strands. Holes in the short fragments of DNA are fixed by joining S and P sides of the segment with the enzyme Ligase.

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19
Q

Enzyme that unzips DNA

A

Helicase

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20
Q

enzyme that adds free nucleotides to growing strands

A

DNA polymerase

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21
Q

enzyme that connects short strands of DNA together

A

DNA ligase

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22
Q

What is the central dogma of biology?

A

information flows from DNA to RNA to Protein

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23
Q

What is the process of DNA becoming RNA with the help of DNA dependent RNA polymerase

A

Transcription

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24
Q

What is the process of RNA becoming a protein

A

Translation

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25
Where/what is mRNA used?
mRNA is used at the ribosomes to make proteins and contains codes to make proper sequence for amino acids to make proteins
26
What leads to different proteins?
Differences in genes (DNA sequence)
27
segment of DNA located at a particular place on a chromosome
Gene
28
What does DNA code for?
DNA codes for specific amino acid sequence in a protein or for the RNA that helps make proteins
29
type of RNA that contains the specific code for a specific amino acid
mRNA
30
type of RNA located in the ribosome that makes up the small and large subunits
rRNA
31
type of RNA that has an anticodon that comes from DNA and also has an attached amino acid
tRNA
32
What are the three steps in transcription?
initiation, elongation, and termination
33
Describe transcription in detail
Before transcription, the chromosome must be opened and unwound to make DNA accesible. Then the DNA is unzipped and the DNA-dependent RNA-polymerase comes in. Initiation: recognizes nucleotides and matches them up. Elongation: brings in each of the new nucleotides to the template strands. Termination: the mRNA falls off the single strand of DNA once a wrong sequence comes up and produces a single strand transcript of RNA, and the DNA zips back up.
34
How many possible codons are there (excluding stop codons)
61
35
What is the start codon for proteins?
AUG (methionine)
36
Where are codons found?
mRNA
37
What are the requirements for translation and where does it occur?
Translation requires rRNA, tRNA, mRNA, and amino acids. It occurs in the cytoplasm.
38
How many genes are in a human genome?
just under 20,000
39
What occurs in alternative splicing?
When the RNA is first transcribed, it makes introns and eons. Introns are spliced out when mRNA goes to maturity.
40
What are exons?
Coding DNA
41
What is the area on a strand before AUG?
5' untranslated region
42
What is the area on a strand after the stop codon?
3' untranslated region
43
How do cells control which proteins they make ?
They regulate transcriptional control, regulate translational control, modify the protein, and degradation.
44
What are the four ways to regulate transcription?
1. Turn off individual genes (regulatory proteins). 2. Condense regions of chromosomes. 3. Condense entire chromosomes. 4. miRNA or dsRNA
45
How does the RNAi mechanism work?
dsRNA binds to the protein dicer which cleaves dsRNA into small fragments. One of the RNA strands is leaded into the RISC complex and links the complex to the mRNA strand by base pairing. mRNA is cleaved and destroyed, no protein can be synthesized.
46
What is the net effect of RNAi?
Reduction and amount of protein produced.
47
What are the three types of mutations?
Point mutation, Insertion mutation, deletion mutation
48
How does point mutation occur?
Point mutation is a change in one basepair that occurs if a wrong nucleotide is corrected by an enzyme, and if the old strand is the wrong changed
49
How does sickle cell anemia occur?
One amino acid in hemoglobin is changed from a glutamine to a valine. That change modifies how this protein bonds to other protein subunits in hemoglobin which changed the shape of the blood cell. Hemoglobin becomes worse at moving oxygen in the body and sick people become anemic.
50
What is a silent mutation?
A point mutation that codes for the same amino acid
51
What type of mutations have a neutral function?
They code for a similar amino acid
52
What type of mutations have a lose function?
Mutations that code for a very different amino acid?
53
Why are no effect mutations lethal?
These mutations code for a stop codon
54
Changing one amino acid to another
missense mutation
55
What is it called if a change occurs from an amino acid coding codon to a stop coding codon
nonsense mutation
56
Mutation that involves either an insertion the DNA sequence or a deletion from a DNA sequence?
Frame-Shift mutation
57
What type of frame-shift mutation will affect all codons after the change?
Insertion/Deletion of a single nucleotide base
58
What is binary fission and where does it occur?
Binary fission occurs in bacteria. Circular DNA is replicated. A new membrane is put down. Cells begin to split (constriction), and the cells split (fission).
59
What is used in binary fission?
DNA helicase, DNA polymerase, DNA ligase
60
What are the functions of mitosis?
Growth and development. Mitotic cell division to mitotic cell division and cellular differentiation to repair and maintenance.
61
How is an embryo formed from a cell?
One cell multiplies and differentiates
62
What is the sexual cycle?
Two adult humans form either haploid egg or sperm. They fertilize into a diploid fertilized egg. The egg goes through mitosis differentiation to become an embryo then a baby then an adult.
63
How many homologues are in a human karyotype?
23
64
Where the spindle microtubules originate?
centrioles
65
coordinates the movement of chromosomes during replication and division
Spindle microtubules
66
Protein complex located at the centromere of a chromosome and serves as an attachment site for the spindle microtubules
Kinetochore
67
What occurs in prophase?
Chromosomes condense and shorten, and the centrioles begin to move apart as the spindle microtubules form. Then the nucleolus dissapears and the nuclear envelope breaks down as the microtubules attach to kinetochores (centromere)
68
What occurs in metaphase?
Spindle microtubules line up chromosomes in the middle of the cell, and the kinetochores align at the cell's equator.
69
What occurs in anaphase?
sister chromatids are ripped apart, and free spindle fibers push poles apart. The chromatids become independent chromosomes
70
What occurs in telophase?
The chromosomes begin unwinding and the nuclear envelope reforms
71
What happens in cytokinesis?
the cytoplasm is divided along the equator. The organelles also have to replicate to end up in the daughter cells
72
How are sister chromatids separated in mitosis?
In metaphase, the sister chromatids are held together at the centromere. At the end of metaphase, the centromere releases the sister chromatids. In anaphase, the sister chromatids move to opposite poles.
73
What are the events of cytokinesis?
Microfilaments form a ring around the equator and contract. The "waist" pinches off
74
What are the advantages/disadvantages of Asexual Reproduction?
Pro: Can make a lot quickly and easily. Con: no variability when the environment changes.
75
What are the advantages/disadvantages of Sexual Reproduction?
Pro: a lot of variability when the environment changes. Con: neither quick nor easy.
76
What occurs in each phase of Meiosis 1?
In prophase 1, homologous chromosomes pair and cross over. In metaphase 1, homologous chromosomes exchange DNA and align on the equator. In anaphase 1, homologous chromosomes move to opposite poles. In telophase 1, the cell produces 2 daughter cells with one copy of each chromatid.
77
What does meiosis produce?
4 haploid cells. Either egg or sperm.
78
What two steps lead to genetic variability?
Genetic recombination (crossing over) and random assortment
79
refers to the exchange of genetic material among chromos
genetic recombination
80
What is the difference between the spindles in meiosis and mitosis?
Meiosis: duplicated chromosomes with one kinetochore; pair homologues go to opposite poles. Mitosis: duplicated chromosomes with two kinetochores; unpaired homologs split between sister chromatids, which go to opposite poles.
81
Who is all of modern day genetics based on?
Gregor Mendel
82
law that states pairs of genes are separated during gamete formation
law of segregation
83
What was mendel's hypothesis for heredity?
Each train is determined by a pair of genes. Law of Segregation. Random chance determines which gene goes to which gamete. There may be more than one form of a gene.
84
What makes a dominant allele different from a recessive allele?
Differences in DNA sequences caused by mutations and the source of new version of genes is mutations.
85
a cross between an unknown genotype to a known genotype
Test Cross
86
Who determines the sex of the offspring?
male
87
chromosomes that occur in homologous pairs in both males and females
autosomes
88
genes found on 1 type of sex chromosomes
sex-linked genes
89
occurs if both alleles are expressed
codominant
90
what type of proteins come off of the red blood cell?
glycoprotein
91
Which gene carries a trait?
recessive
92
a disease that involves deterioration of the nervous system as the recessive gene becomes dominant
Huntington's disease
93
What are some examples of sex-linked (X-linked) disorders?
Color blindness, male-pattern baldness, hemophilia
94
chromosomes are not separated appropriately during meiosis I or II
non-disjunction
95
How does non-disjunction affect chromosomes?
Will produce either more or less chromosomes than should be there
96
What is the cause of Down's Syndrome?
Trisonomy 21. An extra 21st chromosomes, and this disease is linked to maternal age
97
What are characteristics of Down's and how often does it occur?
mental retardation, short stature, particular facial features. Occurs in 1/700 children
98
How are chromosomes condensed?
Wrap them around histones

Biol 1201 (4 decks)

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