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BIO 110 > Chapter 11 > Flashcards

Chapter 11 Flashcards

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Biology 101 flashcards
1
Q

What is the genetic material?

A

Four criteria necessary for genetic material:
Information
Replication
Transmission
Variation

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2
Q
  1. Late 1800s – _____ ______ ____ ____ postulated
  2. Researchers became convinced that _______ carry the genetic information
  3. 1920s to 1940s – scientists expected the _______ portion of chromosomes would turn out to be the genetic material
A
  1. biochemical basis of heredity
  2. chromosomes
  3. protein
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3
Q

Levels of DNA Structure:

A
  1. Nucleotides
  2. Strand
  3. Double helix
  4. Chromosomes
  5. Genome
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4
Q

Nucleotides

A

the building blocks of DNA and RNA

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5
Q

Strand

A

a linear polymer strand of DNA or RNA

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6
Q

Double helix

A

the two strands of DNA

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7
Q

Chromosomes

A

DNA associated with an array of different proteins into a complex structure

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8
Q

Genome

A

the complete complement of genetic material in an organism

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9
Q

DNA is formed from ____

A

nucleotides (A, G, C, T)

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10
Q

DNA
Nucleotides composed ofthree components
1.
2.
3

A
  1. Phosphate group
  2. Pentose sugar
    Deoxyribose
    DNA = Deoxyribonucleic Acid
  3. Nitrogenous base
    Purines – Adenine (A), Guanine (G)
    Pyrimidines – Cytosine (C), Thymine (T)
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11
Q

RNA is formed from ____

A

nucleotides (A, G, C, U)

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12
Q

RNA
Nucleotides composed ofthree components
1.
2.
3.

A

Phosphate group
Pentose sugar
Ribose
RNA = Ribonucleic Acid
Nitrogenous base
Purines – Adenine (A), Guanine (G)
Pyrimidines – Cytosine (C), Uracil (U)

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13
Q

Nucleotide Numbering System
Sugar carbons are
Base attached to
Phosphate attached to

A
  1. 1’ to 5
  2. 1’ carbon on sugar
  3. 5’ carbon on sugar
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14
Q

DNA strands
Nucleotides are ____ bonded

A

covalently

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15
Q

Phosphodiester bond

A

phosphate group links two sugars

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16
Q

Backbone

A

formed from phosphates and sugars
Bases project away from backbone
Written 5’ to 3’
Example: 5’ – TACG – 3’

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17
Q

Solving the Structure of DNA
1. 1953, _____ and ______, proposed the structure of the DNA double helix
2. Watson and Crick used Linus Pauling’s method of working out protein structures using simple ________ models
3. ________’s X-ray diffraction results were crucial evidence, suggesting a helical structure with uniform diameter

A
  1. James Watson and Francis Crick
  2. ball-and-stick
  3. Rosalind Franklin’s
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18
Q

Base-pairing
Erwin Chargoff analyzed base composition of DNA from many different species
Results consistently showed:
amount of adenine (A) = amount of _____-
amount of cytosine (C) = amount of________

A

amount of adenine (A) = amount of thymine (T)
amount of cytosine (C) = amount of guanine (G)

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19
Q

Watson and Crick
Put together these pieces of information
Found ball-and-stick model consistent with data:
1.
2.
James Watson, Francis Crick, and Maurice Wilkins awarded Nobel Prize in 1962
Rosalind Franklin had died and the Nobel Prize is not awarded posthumously

A

ball-and-stick
1. Double-stranded helix
2. Base-pairing: A with T and G with C

20
Q

Features of DNA

A

Double stranded
Antiparallel strands
Right-handed helix
Sugar-phosphate backbone
Bases on the inside
Stabilized by H-bonding
Specific base-pairing
Approximately 10 nts per helical turn

21
Q

DNA Structure - Putting it All Together
Chargoff’s rule:

A

A pairs with T
G pairs with C
Keeps width consistent

22
Q

Complementary DNA strands:

A

5’ – GCGGATTT – 3’
3’ – CGCCTAAA – 5’

23
Q

Antiparallel strands:

A

One strand 5’ to 3’
Other stand 3’ to 5’

24
Q

Grooves are revealed in the space-filling model
1. ______
Proteins bind to affect gene expression
2. ______
Narrower

A
  1. Major groove
  2. Minor groove
25
Q

DNA Replication: Semiconservative Mechanism

A

DNA replication produces DNA molecules with 1 parental stand and 1 newly made daughter strand

26
Q

DNA Replication: Conservative Mechanism

A

DNA replication produces 1 double helix with both parental strands and the other with 2 new daughter strands

27
Q

DNA Replication: Dispersive Mechanism

A

DNA replication produces DNA strands in which segments of new DNA are interspersed with the parental DNA

28
Q

DNA Replication
1. The ____ ___ ___ ____ and serve as template strands
2. New nucleotides must obey the ____ rule
3. End result: _____new double helices with same base sequence as original

A

1.two parental strands separate
2. AT/GC rule
3. two

29
Q

_____ of ______ provides an opening called a replication bubble that forms two replication forks

A

Origin of replication

30
Q

DNA replication proceeds outward from forks
Bacteria have _____ _____of replication
Eukaryotes have ____ ____of replication

A
  1. single origin
  2. multiple origins
31
Q

Role and Features of DNA Polymerase
DNA polymerase -Covalently links nucleotides
1. Uses (dNTPS) Deoxynucleoside triphosphates
2. DNA polymerase _____ ___ ___ on a bare template strand
3. Requires a _____ to get started
4. DNA polymerase only ____

A
  2. cannot begin synthesis
  3. primer
  4. works 5’ to 3’
32
Q

Deoxynucleoside triphosphates

A

Free nucleotides with three phosphate groups
Breaking covalent bond to release pyrophosphate (two phosphates) provides energy to connect nucleotides

33
Q

Comparison of the leading and lagging strands

Leading strand

A

DNA synthesized in as one long molecule
DNA primase makes a single RNA primer
DNA polymerase adds nucleotides in a 5’ to 3’ direction as it slides forward

34
Q

Lagging strand

A

DNA synthesized 5’ to 3’ but as Okazaki fragments
Okazaki fragments consist of RNA primers plus DNA

35
Q

In both strands- leading and lagging strands

A

RNA primers are removed by DNA polymerase and replaced with DNA
DNA ligase joins adjacent DNA fragments

36
Q

DNA replication is very accurate
Three mechanisms for accuracy
1. _______ ______between A and T, and between G and C is more stable than mismatched combinations
2. Active site of___ ______ is unlikely to form bonds if pairs mismatched
3. DNA polymerase can proofread to remove mismatched pairs
DNA polymerase backs up and digests linkages
Other DNA repair enzymes as well

A
  1. Hydrogen bonding
  2. DNA polymerase
37
Q

Important issues for DNA polymerase are:

A

speed,
fidelity,
Completeness.

38
Q

DNA Polymerases Are a Family of Enzymes With Specialized Functions
1. Nearly all living species have ______ of DNA polymerase
2. Genomes of most species have several DNA polymerase genes due to _______
3. Independent genetic changes produce enzymes with _____

A
  1. more than one type
  2. gene duplication
  3. specialized functions
39
Q

DNA Polymerases: Prokarytotes
E. coli has 5 DNA polymerases

A

DNA polymerase III – multiple subunits, responsible for majority of replication
DNA polymerase I – a single subunit, rapidly removes RNA primers and fills in DNA
DNA polymerases II, IV and V – DNA repair and can replicate damaged DNA
DNA polymerases I and III stall at DNA damage
DNA polymerases II, IV and V don’t stall but go slower and make sure replication is complete

40
Q

DNA Polymerases: Eukaryotes
Humans have 12 or more DNA polymerases

A

Designated with Greek letters
DNA polymerase a-– its own built in primase subunit
DNA polymerase o and e- – extend DNA at a faster rate
DNA polymerase y- – replicates mitochondrial DNA

41
Q

Telomeres
1.Series of short nucleotide sequences repeated ____ in eukaryotes
2. Specialized form of DNA replication only in _____ in the telomeres
3. Telomere at 3’ does not have a complementary strand and is called _____

A
  1. at the ends of chromosomes
  2. eukaryotes
  3. a 3’ overhang
42
Q

DNA replication by telomeres
1. DNA polymerase __ ____the tip of the strand with a 3’ end
2.___ ____ for upstream primer to be made
3. If this replication problem were not solved, linear chromosomes would become ___ ____
4.___ ____attaches many copies of DNA repeat sequence to the ends of chromosomes

A
  1. cannot copy
    2 No place
  2. progressively shorter
  3. Telomerase enzyme
43
Q

Molecular structure of eukaryotic chromosomes
Typical eukaryotic chromosome may be hundreds of millions of base pairs long
Length would be 1 meter
But must fit in cell 10 to 100 micrometer
1. _____ - Discrete unit of genetic material
2. Chromosomes ____ of _____ a DNA-protein complex

A
  1. Chromosome
  2. composed of chromatin
44
Q

Three levels of DNA compaction

A
  1. DNA wrapping
  2. 30-nanometer fiber
  3. Radial loop domains
45
Q
  1. DNA wrapping
A

DNA wrapped around histones to form nucleosome
Shortens length of DNA molecule 7-fold

46
Q
  1. 30-nanometer fiber
A

Current model suggests asymmetric, 3D zigzag of nucleosomes
Shortens length another 7-fold

47
Q
  1. Radial loop domains
A

Interaction between 30-nanometer fibers and nuclear matrix
Each chromosome located in discrete territory
Level of compaction is not uniform:
Heterochromatin - highly compact chromatin.
Euchromatin - loosely compact chromatin.

BIO 110 (6 decks)

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