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
Q

Where/what is mRNA used?

A

mRNA is used at the ribosomes to make proteins and contains codes to make proper sequence for amino acids to make proteins

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26
Q

What leads to different proteins?

A

Differences in genes (DNA sequence)

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27
Q

segment of DNA located at a particular place on a chromosome

A

Gene

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28
Q

What does DNA code for?

A

DNA codes for specific amino acid sequence in a protein or for the RNA that helps make proteins

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29
Q

type of RNA that contains the specific code for a specific amino acid

A

mRNA

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30
Q

type of RNA located in the ribosome that makes up the small and large subunits

A

rRNA

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31
Q

type of RNA that has an anticodon that comes from DNA and also has an attached amino acid

A

tRNA

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32
Q

What are the three steps in transcription?

A

initiation, elongation, and termination

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33
Q

Describe transcription in detail

A

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.

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34
Q

How many possible codons are there (excluding stop codons)

A

61

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35
Q

What is the start codon for proteins?

A

AUG (methionine)

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36
Q

Where are codons found?

A

mRNA

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37
Q

What are the requirements for translation and where does it occur?

A

Translation requires rRNA, tRNA, mRNA, and amino acids. It occurs in the cytoplasm.

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38
Q

How many genes are in a human genome?

A

just under 20,000

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39
Q

What occurs in alternative splicing?

A

When the RNA is first transcribed, it makes introns and eons. Introns are spliced out when mRNA goes to maturity.

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40
Q

What are exons?

A

Coding DNA

41
Q

What is the area on a strand before AUG?

A

5’ untranslated region

42
Q

What is the area on a strand after the stop codon?

A

3’ untranslated region

43
Q

How do cells control which proteins they make ?

A

They regulate transcriptional control, regulate translational control, modify the protein, and degradation.

44
Q

What are the four ways to regulate transcription?

A
  1. Turn off individual genes (regulatory proteins). 2. Condense regions of chromosomes. 3. Condense entire chromosomes. 4. miRNA or dsRNA
45
Q

How does the RNAi mechanism work?

A

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
Q

What is the net effect of RNAi?

A

Reduction and amount of protein produced.

47
Q

What are the three types of mutations?

A

Point mutation, Insertion mutation, deletion mutation

48
Q

How does point mutation occur?

A

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
Q

How does sickle cell anemia occur?

A

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
Q

What is a silent mutation?

A

A point mutation that codes for the same amino acid

51
Q

What type of mutations have a neutral function?

A

They code for a similar amino acid

52
Q

What type of mutations have a lose function?

A

Mutations that code for a very different amino acid?

53
Q

Why are no effect mutations lethal?

A

These mutations code for a stop codon

54
Q

Changing one amino acid to another

A

missense mutation

55
Q

What is it called if a change occurs from an amino acid coding codon to a stop coding codon

A

nonsense mutation

56
Q

Mutation that involves either an insertion the DNA sequence or a deletion from a DNA sequence?

A

Frame-Shift mutation

57
Q

What type of frame-shift mutation will affect all codons after the change?

A

Insertion/Deletion of a single nucleotide base

58
Q

What is binary fission and where does it occur?

A

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
Q

What is used in binary fission?

A

DNA helicase, DNA polymerase, DNA ligase

60
Q

What are the functions of mitosis?

A

Growth and development. Mitotic cell division to mitotic cell division and cellular differentiation to repair and maintenance.

61
Q

How is an embryo formed from a cell?

A

One cell multiplies and differentiates

62
Q

What is the sexual cycle?

A

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
Q

How many homologues are in a human karyotype?

A

23

64
Q

Where the spindle microtubules originate?

A

centrioles

65
Q

coordinates the movement of chromosomes during replication and division

A

Spindle microtubules

66
Q

Protein complex located at the centromere of a chromosome and serves as an attachment site for the spindle microtubules

A

Kinetochore

67
Q

What occurs in prophase?

A

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
Q

What occurs in metaphase?

A

Spindle microtubules line up chromosomes in the middle of the cell, and the kinetochores align at the cell’s equator.

69
Q

What occurs in anaphase?

A

sister chromatids are ripped apart, and free spindle fibers push poles apart. The chromatids become independent chromosomes

70
Q

What occurs in telophase?

A

The chromosomes begin unwinding and the nuclear envelope reforms

71
Q

What happens in cytokinesis?

A

the cytoplasm is divided along the equator. The organelles also have to replicate to end up in the daughter cells

72
Q

How are sister chromatids separated in mitosis?

A

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
Q

What are the events of cytokinesis?

A

Microfilaments form a ring around the equator and contract. The “waist” pinches off

74
Q

What are the advantages/disadvantages of Asexual Reproduction?

A

Pro: Can make a lot quickly and easily. Con: no variability when the environment changes.

75
Q

What are the advantages/disadvantages of Sexual Reproduction?

A

Pro: a lot of variability when the environment changes. Con: neither quick nor easy.

76
Q

What occurs in each phase of Meiosis 1?

A

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
Q

What does meiosis produce?

A

4 haploid cells. Either egg or sperm.

78
Q

What two steps lead to genetic variability?

A

Genetic recombination (crossing over) and random assortment

79
Q

refers to the exchange of genetic material among chromos

A

genetic recombination

80
Q

What is the difference between the spindles in meiosis and mitosis?

A

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
Q

Who is all of modern day genetics based on?

A

Gregor Mendel

82
Q

law that states pairs of genes are separated during gamete formation

A

law of segregation

83
Q

What was mendel’s hypothesis for heredity?

A

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
Q

What makes a dominant allele different from a recessive allele?

A

Differences in DNA sequences caused by mutations and the source of new version of genes is mutations.

85
Q

a cross between an unknown genotype to a known genotype

A

Test Cross

86
Q

Who determines the sex of the offspring?

A

male

87
Q

chromosomes that occur in homologous pairs in both males and females

A

autosomes

88
Q

genes found on 1 type of sex chromosomes

A

sex-linked genes

89
Q

occurs if both alleles are expressed

A

codominant

90
Q

what type of proteins come off of the red blood cell?

A

glycoprotein

91
Q

Which gene carries a trait?

A

recessive

92
Q

a disease that involves deterioration of the nervous system as the recessive gene becomes dominant

A

Huntington’s disease

93
Q

What are some examples of sex-linked (X-linked) disorders?

A

Color blindness, male-pattern baldness, hemophilia

94
Q

chromosomes are not separated appropriately during meiosis I or II

A

non-disjunction

95
Q

How does non-disjunction affect chromosomes?

A

Will produce either more or less chromosomes than should be there

96
Q

What is the cause of Down’s Syndrome?

A

Trisonomy 21. An extra 21st chromosomes, and this disease is linked to maternal age

97
Q

What are characteristics of Down’s and how often does it occur?

A

mental retardation, short stature, particular facial features.
Occurs in 1/700 children

98
Q

How are chromosomes condensed?

A

Wrap them around histones