Chapter 6: Molecular Genetics Flashcards Preview

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Flashcards in Chapter 6: Molecular Genetics Deck (97):
1

genetic material

hereditary information

2

gamete

sex cells

3

autosomal cells

body cells

4

minimal medium

the minimum amount of material needed to grow

5

spore

an asexual seed

6

virulent

extremely harmful of toxic

7

bacteriophage

a virus that infects and destroys bacteria

8

double helix

a double-stranded spiral that makes up DNA molecular structure

9

pyrimidine

a nitrogenous base with a characteristic single ring structure (hint: cytosine and thymine)

10

purine

a nitrogenous base with a two ring characteristic structure (hint: adenine and guanine)

11

antiparallel

the overall direction of two complementary strands relative to one another such that their 5' to 3' orientation run opposite of each other

12

isotopes

different forms of an element that have the same number of protons and a different number of neutrons and atomic mass

13

differential centrifugation

a technique that involves the separation of cellular particles according to their mass, size, or density

14

polymerization

a process by which a large molecule is constructed

15

phosphodiester linkages

the linkages that hold nucleotides together

16

DNA polymerase

the enzyme that catalyzes the polymerization of new DNA strands

17

helicase

an enzyme that unwinds the double-stranded DNA before replication at the site of the replication fork

18

single strand binding protein

an enzyme that stabilizes the unwound helix during replication

19

RNA primer

a strand of RNA nucleotides that is required for DNA synthesis

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primase

an enzyme that synthesizes RNA primer

21

okazaki fragments

small pieces of nucleotide that are used to synthesize DNA from the lagging strand

22

ligase

an enzyme responsible for joining Okazaki fragments into a single DNA strands

23

DNA polymerase I

an enzyme that assists in removing RNA primers from a DNA strand, replacing them with DNA

24

leading strand

the strand of DNA of grows continuously in the direction of the replication fork, and can be read easily

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lagging strand

the strand of DNA that grows away from the replication fork, and cannot be read easily

26

excision repair

an incorrect DNA sequence is cut out and replaced with the correct sequence

27

telomeres

repeating sequences of nucleotide found at the end of DNA strands, which are made up of tandem repeats

28

telomerase

an enzyme that can polymerize telomere sequences

29

polypeptide

a chain of amino acids joined by peptide bonds

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transcription

the process where information on DNA is coded into a messenger RNA molecule

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translation

information on the messenger RNA molecule is converted by a ribosome into a polypeptide strand

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codon

3 bases on an mRNA strand that designate a particular amino acid

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transcription unit

the sequence on the DNA strand to be coded in mRNA

34

promoter sequence

a series of DNA nucleotides (15-300 base pairs long) that serves as the site where RNA polymerase binds

35

transcription factors

a collection of proteins that help RNA polymerase recognize and bind to the promoter

36

terminator sequence

DNA nucleotides that signal the end of transcription

37

poly (A) tail

consists of 30-200 adenine nucleotides and is attached to the 3' end of the mRNA molecule. It protects against degradation and helps export mRNA from the nucleus.

38

introns

intervening sequences of noncoding nucleotides that occur between coding sequences

39

exons

expressed sequences of the mRNA transcript

40

spliceosomes

a composition of proteins and small nuclear Ribonuclear Proteins (hint: snRNPs)

41

anticodon loop

contains a sequence of 3 nucleotides (anticodon) which are complementary to 3 nucleotides (codon) on the mRNA strand

42

nucleolus

a site in the nucleus where ribosomal RNA is synthesized and ribosomes are assembled

43

redundancy/degeneracy

describes the relative unimportance the third nucleotide plays for specifying a given amino acid (hint: ACU and ACC both specify for the amino acid threonine)

44

charged tRNA

a tRNA molecule bound to an amino acid with a high energy covalent bond (hint: also called aminoacyl tRNA)

45

ribozymes

enzymes made of RNA that assist in RNA splicing

46

elongation

the addition of amino acids one by one to form a polypeptide chain

47

codon recognition

the anticodon of the tRNA binds with the complimentary sequences of the mRNA codon

48

peptide bond

covalent links that form by dehydration reactions between amino acids

49

stop codon

1 of 3 sequences of three nucleotides on the mRNA strand, (UAG, UAA, or UGA) which accepts a protein release factor, thus terminating elongation

50

polyribosomes

several ribosomes attached to an mRNA strand that increase efficiency of translation. They occur in prokaryotes and eukaryotes.

51

signal peptides

sequences of about 20 amino acids on polypeptides that direct a protein to the ER

52

lac operon

regulates mRNA transcription of enzymes responsible for digesting lactose

53

transcriptional controls

control whether or not mRNA is produced

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gene expression

transcription and translation to form a polypeptide

55

repressor protein

a protein that binds to an operator site and blocks RNA polymerase

56

operator/operator site

the site downstream from the promoter where the repressor protein binds

57

inducible operon

a regulatory unit that is activated when a small molecule interacts with a regulatory protein

58

repressible operon

a regulatory unit that is inhibited when a small molecule binds with a regulatory protein

59

allolactose

an isomer of lactose

60

operon

a unit of genetic function that consists of regulated sets of genes with related functions

61

allosteric site

a specific receptor site on an enzyme apart from the active site. Molecules bind here and change the shape of the active site.

62

genome

the DNA in a complete set of an organism's chromosomes (both coding for proteins and non-coding DNA)

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chromosome

a highly compacted form of DNA and associate proteins

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nucleosome

a segment of DNA wrapped around a core of histone proteins

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chromatin

a complex of DNA and proteins in eukaryotes

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domains

the loops of third level DNA, where chromatin fiber is looped and anchored onto a scaffold protein

67

denature

the separation of the two strands of the DNA double helix by breaking hydrogen bonds

68

tandem repeats/satellite DNA

sequences of DNA that repeat one after the other up to several hundred thousand times (ie: GTTAC GTTAC GTTAC, etc.)

69

interspersed repetitive DNA

sequences of repetitive DNA which are scattered throughout the genome. These sequences are not always identical, but must be similar.

70

reanneal

the coming-together of DNA strands

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centromere

the region of a chromosome that joins two sister chromatids, and is made up of multiple tandem repeat sequences

72

gene family

long, repeating DNA sequences that can code for genes and are capable of transcribing RNA

73

pseudogenes

copies of existing genes that lack regulatory sequences that are necessary for gene expression

74

gene amplification

takes place when many copies of a gene are synthesized in order to increase production of the gene product (hint: salamander eggs and cancer cells)

75

transposon/jumping genes

a segment of DNA that is able to copy itself and insert this copy elsewhere in a chromosome

76

retrotransposons

a transposable element that moves within a genome by means of an RNA intermediate

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histone

a small protein involved in DNA packing

78

nucleoid

region where DNA concentrations are found in prokaryotic cells

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gene controls

methods used to ensure that certain genes are only expressed when needed

80

totipotent

containing a full set of hereditary instructions

81

transformation

transfer of genetic material from one cell to another

82

complementarity

sets of hydrogen bonds link base pairs together (2 hydrogen bonds between thymine and adenine, and 3 hydrogen bonds between guanine and cytosine)

83

endonucleases

cut DNA internally

84

exonucleases

chews away at the end of DNA, helps proofread, and is used by DNA polymerase I to remove the primers after replication

85

replisome

a replication organelle, made up of an assembly of proteins

86

primosome

made up of primase/helicase and other proteins

87

gene

a sequence of nucleotides that determines the amino acid sequence of a protein

88

triplet code

the 3-nucleotide sequence in each codon

89

reading frame

part of the genetic code that is read by mRNA

90

template strand (antisense strand)

the strand of DNA that is copied

91

coding strand (sense strand)

the strand of DNA that is not copied, and is identical to RNA

92

-35 sequence

TTGACA, which is 35 nucleotides away from where transcription starts

93

-10 sequence

TATAAT, which is 10 nucleotides from where transcription starts

94

transcription bubble

the area containing RNA polymerase, DNA, and the growing mRNA strand

95

CG hairpin

causes polymerase to pause and let go of DNA

96

nonsense codons

UAA, UAG, UGA

97

initiation factors

proteins that position tRNAfMet (in prokaryotes) or methionine (in eukaryotes) at the P site