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SAT II Biology > Chapter 7 > Flashcards

Chapter 7 Flashcards

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1
Q

What did scientists believe up until the early 1950s?

A

that proteins were the molecules that make up genes and constitute inherited material

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2
Q

Griffith (1927)

A

discovered the natural phenomenon known as bacterial transformation

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3
Q

What is bacterial transformation?

A

the ability of bacteria to alter their genetic makeup by absorbing foreign DNA molecules from other bacterial cells and incorporating the foreign DNA into their own.

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4
Q

What did Griffith work with?

A

different strains of the bacterium Diplococcus pneumoniae, which causes pneumonia

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5
Q

Avery , MacLeod, and McCarty (1944)

A

published findings that the molecule that Griffith’s bacteria was transferring was DNA

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6
Q

Avery , MacLeod, and McCarty (1944)

2nd discovery

A

Provided direct experimental evidence that DNA is the genetic material

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7
Q

Hershey and Chase (1952)

A

proved that DNA, not proteins, is the molecule of inheritance when they tagged bacteriophages (viruses that attack bacteria) with the radioactive isotopes 32P and 35S

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8
Q

32P labeled the

35S labeled the

A

dna of the phage viruses

protein coat of the phage viruses

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9
Q

Hershey + Chase found that when bacteria are infected with phage viruses

A

32p from the virus entered the bacterium and produced thousands of progeny. However, no 35s entered the bacterium

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10
Q

Rosalind Franklin (1950-53)

A

continued the work begun by Maurice Wilkins

-carrying out the xray crystallography analysis of dna that showed dna to be a helix

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11
Q

Her work helped watson and crick in

A

developing their model of DNA

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12
Q

Watson and Crick received the nobel prize in 1962 for

A

correctly describing the structure of dna as a double helix

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13
Q

Meselson and Stahl (1953)

A

proved Watsona and Crick’s hypothesis that DNA replicates in a semiconservative fashion

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14
Q

Meselson and Stahl’s experiment

A

they cultured bacteria (replicating bacteria in controlled settings) in a medium containing heavy nitrogen (15N) and then moved them to a medium containing light nitrogen (14N) allowing the bacteria to replicate and divide once

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15
Q

Results of Meselson and Stahl Experiment

A

new bacterial DNA contained DNA consisting of 1 heavy strand and 1 light one proving Watson and crick’s theory

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16
Q

Structure of DNA

A
  • Double helix shaped like a twisted ladder

- Consists of 2 complementary strands running in opposite directions from each other

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17
Q

DNA is a

A

Polymer made of repeating units called nucleotides

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18
Q

Each nucleotide consists of a

DNA

A

5-carbon sugar (deoxyribose), a phosphate molecule, and a nitrogenous base

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19
Q

Each nucleotide contains

A

1 of 4 possible nitrogenous bases → adenine (A), thymine (T), cytosine ( C ), and guanine (G)

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20
Q

What does A bond with?

What does C bond with?

A

T

G

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21
Q

Nucleotides of opposite chains are paired to

A

ne another by hydrogen bonds

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22
Q

DNA replication is

A

the making of an exact replica of DNA

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23
Q

The 2 new molecules of DNA that are produced

A

each consist of 1 new strand and 1 old strand

this is called semiconservative replication

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24
Q

When does DNA replication occur?

A

during interphase in the life cycle of a cell

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25
Q

What does DNA polymerase do?

A
  1. catalyzes (speeds up reaction) the replication of the new DNA
  2. proofreads each new DNA strand, fixing errors and minimizing the occurrence of mutations
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26
Q

Where does DNA unzip?

A

at the hydrogen bonds that connect the two strands of the double helix

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27
Q

Each strand of DNA serves as a template for

A

the new strand according to the base-pairing rules → A w/ T, C w/ G

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28
Q

Each time the DNA replicates

A

some nucleotides from ends of chromosomes are lost

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29
Q

How does DNA protect itself against possible loss?

A

some eukaryotic cells have special nonsense nucleotide sequences at the ends of chromosomes that repeat thousands of times → called telomeres

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30
Q

RNA

A

single-stranded helix

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31
Q

Each nucleotide consists of

RNA

A

5-carbon sugar (ribose), phosphate, and a nitrogenous base

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32
Q

(RNA) Each nucleotide contains one of the four possible nitrogenous bases →

A

adenine (A), uracil (U), cytosine ( C), and guanine (G)

Uracil replaces thymine → no thymine in RNA

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33
Q

3 types of RNA

A

mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA)

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34
Q

mRNA

A

carries messages directly from DNA in nucleus to the cytoplasm during the making of protein.

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35
Q

The triplet nucleotides of mRNA (such as AAC or UUU) are called

A

codons

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36
Q

tRNA

A

shaped like a clover leaf and carries amino acids to mRNA at the ribosome in order to form a polypeptide.

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37
Q

The triplet nucleotides of tRNA are

A

complementary to the codons of mRNA and are called anticodons

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38
Q

rRNA

A

structural, along with proteins, it makes up the ribosome.

38
Q

rRNA

A

structural, along with proteins, it makes up the ribosome.

39
Q

rRNA

A

structural, along with proteins, it makes up the ribosome.

40
Q

Protein Synthesis

3 Main steps

A

transcription, RNA processing, and translation

41
Q

Transcription

A

The process by which DNA makes RNA → facilitated by RNA polymerase and occurs in the nucleus

42
Q

Transcription: The triplet code in DNA is transcribed

A

into a codon sequence in mRNA following the base-pairing rules → A w/ U and C w/ G

43
Q

If the sequence in DNA triplets is AAA TAAA CCG GAC

A

The complementary sequence of codons in mRNA is: UUU AUU GGC CUG

44
Q

RNA Processing

A

Initial transcript is processed or edited by a series of enzymes → after transcription but before the newly formed strand of RNA is shipped out of the nucleus to the ribosome

45
Q

RNA processing:

Enzymes remove pieces of RNA that do not code for any protein→

A

non-coding regions that are removed are called introns (intervening sequences)

46
Q

RNA processing:

The remaining portions, exons (expressed sequences or coding regions), are

A

pieced back together to form the final transcript

47
Q

As a result of RNA processing, the mRNA that leaves the nucleus is a great deal

A

shorter than the piece that was initially transcribed

48
Q

Translation of mRNA into Protein

A

Translation is the process by which the mRNA sequence is converted into an amin acid sequence

49
Q

Translation of mRNA into protein occurs at

A

the ribosome

50
Q

Translation of mRNA into Protein :

Amino acids present in the cytoplasm are carried by tRNA molecules to the

A

codons of the mRNA strand at the ribosome according the base-pairing rules ( A w/ U and C w/ U)

51
Q

Some tRNA molecules can bind to

A

2 or more different codons

For ex, codons UCU, UCC, UCA, and UCG all code for a single amino acid, serine

52
Q

Every cell does not constantly synthesize every

A

polypeptide it has the ability to make

53
Q

Operon

A

is a cluster of functional genes plus the switches that turn them on and off

54
Q

2 types of operons are

A

lac or inducible operon

repressible operon

55
Q

Lac or inducible operon

A

is normally turned off unless it is actively induced or triggered to turn on by something in the environment

56
Q

Repressible operon

A

is always turned on unless it is actively turned off bc it is temporarily not needed

57
Q

Parts of the operon

A

promoter , operator, TATA box

58
Q

Promoter

A

binding site of RNA polymerase

59
Q

Promoter must always bind to DNA before

A

transcription can take place so the promoter is like an ‘on’ switch

60
Q

Operator

A

binding site for the repressor which turns off the Lac operon

60
Q

Operator

A

binding site for the repressor which turns off the Lac operon

61
Q

TATA box (named for its sequences of alternating adenine and thymine)

A

helps RNA polymerase bind to the promoter

62
Q

Changes in genetic material

A

occur spontaneously and at random and can be caused by mutagenic agents

63
Q

Mutations are the

A

raw material for natural selection

64
Q

Several gene mutations can occur :

A

point mutations, insertions, and deletions.

65
Q

Point mutation

A

simplest mutation

a base-pair substitution, where one nucleotide converts to another

66
Q

Ex. of point mutation

Normal: THE FAT CAT SAW THE DOG

A

becomes THE FAT CAT SAW THE HOG

67
Q

Sickle cell anemia results from

A

point mutation in the gene that codes for hemoglobin

68
Q

Abnormal hemoglobin causes RBCs to

A

sickle when available oxygen is low

69
Q

When RBCs sickle, a variety of tissues may be

A

deprived of oxygen and suffer severe and permanent damage

70
Q

Insertion or Deletion

A

results form a single nucleotide insertion or deletion (the addition or deletion of one letter in the DNA sequence)

71
Q

(insertion/deletion) Both mutations result in

A

a frameshift bc the entire reading frame is altered and unreadable

72
Q

A frameshift can

A

cause formation of altered polypeptide or no polypeptide at all

73
Q

Chromosome Mutations

A

Alterations in chromosome number or structure and are visible under a microscope

74
Q

Aneuploidy and polyploidy both result from nondisjunction

A

where homologous pairs fail to separate during meiosis

75
Q

The human genome (an organism’s genetic material) consists of

A

3 billion base pairs of DNA and about 20,000 genes

76
Q

97% of our DNA

A

doesn’t code for protein product

77
Q

Some DNA consists of:

A
  • regulatory sequences the control gene expressions
  • Introns that interrupt genes
  • (majority consists of) repetitive sequences that may repeat 10 million times and never get transcribed
  • Psuedogenes → former genes that have accumulated mutations over a long time
78
Q

Recombinant DNA means

A

taking DNA from 2 sources and combining them in one cell

79
Q

Recombinant DNA is used in

A

genetic engineering or biotechnology

80
Q

2 important areas of study in genetic engineering are

A

gene therapy and environmental cleanup

81
Q

Microbes are also being engineered to

A

degrade oil at oil spills or decontaminate harmful chemicals at toxic mining sits or in water treatment plants

82
Q

Growing concern about the safety about GMOs

A
  • GMOs will be released into the wild spreading their engineered genes to wild species
  • Foreign genes might adversely affect people who eat the genetically engineered organisms
83
Q

Restriction Enzymes

A

An important tool for scientists working with DNA → cut DNA at specific recognition sequences or sites such as GAATC and are sometimes referred to as molecular scissors

84
Q

The pieces of DNA that results form the cuts made by restriction enzymes are called

A

restriction fragments

85
Q

100s of different restriction enzymes have been

A

isolated from bacteria

86
Q

Gel Electrophoresis

A

Separates large molecules of DNA on the basis of their rate of movement through agarose gel in an electric field

87
Q

Gel electrophoresis:

the smaller the molecule

A

the faster it runs through the gel

88
Q

If necessary, the concentration of the agarose gel can be changed to

A

provide a better separation of the tiny DNA fragments

89
Q

In order to run DNA through a gel, it must

A

be cut up by restriction enzymes into pieces small enough to migrate through the gel

90
Q

Once separated on a gel,

A

the DNA can be analyzed in many ways

91
Q

Polymerase Chain Reaction

A

Devised in 1985, PCRs are a cell-free, automated technique by which a piece of DNA can be rapidly copied or amplified

92
Q

PCRs:

Billions of copies of a fragment of DNA can be produced in a few hours and once the DNA is amplified

A

these copies can be studied or used in a comparison with other DNA samples

SAT II Biology (15 decks)

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