Ch. 10 Molecular Biology of the Gene Flashcards

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1
Q

Bacteriophage (Phage)

A

A virus that infects bacteria

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2
Q

Molecular Biology

A

The study of the molecular basis of genes and gene expression; molecular genetics.

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3
Q

Nucleotide

A

An organic monomer consisting of a 5-carbon sugar covalently bonded to a nitrogenous base and a phosphate group; building blocks of nucleic acid

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4
Q

Polynucleotide

A

A polymer made up of many nucleotides covalently bonded together

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5
Q

Sugar-phosphate backbone

A

Repeating pattern of sugar phosphate

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6
Q

What are pyrimidines?

A

Single ring of nitrogen and carbon

- Thymine and Cytosine

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7
Q

What are purines?

A

Large double ring

- Adenine and Guanine

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8
Q

What does RNA have that DNA doesn’t?

A

Uracil

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9
Q

Double Helix

A

2 DNA strands with 2 nm diameter

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10
Q

What are 3 major things learned?

A

1) How DNA is hereditary material of life
2) DNA stores information and replicates self
3) DNA controls cells by directing DNA synthesis

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11
Q

Virus

A

Infective substance, packaged genes

  • 1000x smaller than bacterium
  • DNA or RNA
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12
Q

What are the lifelike aspects of a virus?

A

1) Highly organized
2) Contain nucleic acids (RNA or DNA)
3) Experiences reproduction

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13
Q

What are non lifelike aspects of a virus?

A

1) Not cellular (not made of cells)

2) Cannot reproduce on its own (Inert)

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14
Q

Nucleic Acids

A

Polymer/monomers of DNA and RNA

- made of nucleotides

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15
Q

What are the 3 parts of a nucleotide?

A

1) Phosphate group
2) 5 Carbon Sugar (Deoxyribose or ribose)
3) Nitrogen Base

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16
Q

What is a nitrogen base?

A

Rings of nitrogen and carbons with various functional groups attached

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17
Q

What is encoded in the nucleotide sequence?

A

Genetic information in chromosomes

  • how to make proteins
  • makes each organism unique
  • understand/explains life’s process
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18
Q

DNA Replication

A

Process in which genetic instructions are copied before the cell divides

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19
Q

What are the 3 steps of DNA Replication?

A

1) Two parent strands separate to serve as a template for complimentary strand
2) Free nucleotides line along template and connect to corresponding nucleotide according to base pairing
3) Enzymes link nucleotides together to form new DNA strand

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20
Q

Why is DNA replication biochemically complicated?

A

1) DNA must unravel and copy simultaneously

2) Speed! Occurs very rapidly!!

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21
Q

Origin of Replication

A

Site where proteins attach to DNA molecule and separate strands

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22
Q

Replication Bubble

A

Areas where origin of replication are; several exist to reduce time; eventually combine for daughter strands

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23
Q

DNA Polymerase

A

Enzyme that links DNA nucleotides to growing strand (proper location)

  • only adding on 3’ (5’ -> 3’)
  • Adds nucleotides in continuous pieces for one and in discontinuous pieces for another
  • proofreads the sequence and fixes it (repairs DNA damage)
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24
Q

DNA Ligase

A

Enzyme that ties all the pieces intro one strand

- 12 altogether

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25
Q

What does DNA replication ensure?

A

Ensures all somatic cells have same genetic instructions for continuity between generations

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26
Q

What is the 3’ end of a DNA strand?

A

3’ with -OH

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27
Q

What is the 5’ end of DNA strand?

A

5’ with phosphate group

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28
Q

What is the connection between genotype and proteins of phenotype?

A

DNA specifies the synthesis of proteins.

DNA -> RNA -> Proteins

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29
Q

Transcription

A

Transfer of info from DNA to RNA

  • occurs in nucleus
  • uses only 1 DNA strand and hydrogen bonds
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30
Q

Translation

A

Transfer of info from RNA into protein synthesis

  • nucleotide -> amino acid (converts language)
  • occurs in cytoplasm/ribosome
31
Q

What did Archibald Garrod hypothesize?

A

Genes dictate phenotypes thru enzymes, the proteins that catalyze chemical processes in the cell

32
Q

What did Beadle and Tatum hypothesize?

A

“One-Gene One-Polypeptide”

- each polypeptide is specified to its own genre

33
Q

Triplet Code

A

Set of rules giving the correspondence between nucleotide triplets (codons) in mRNA and amino acid in protein

34
Q

Codons

A

A 3 nucleotide sequence in mRNA that specifies a particular amino acid or polypeptide termination sequence; basic unit of the genetic code

35
Q

What is the code for the start of a polypeptide chain?

A

AUG

36
Q

What is the stop/end code for a polypeptide chain?

A

UAA, UAG, UGA

37
Q

RNA Polymerase

A

An enzyme that links together the growing chains of RNA nucleotides during transcription, using a DNA strand as a template

38
Q

Promoter

A

A specific nucleotide sequence in DNA, located at the start of a gene, that is the binding site for RNA Polymerase and the place where transcription begins

39
Q

What are the 3 steps for transcription?

A

1) Initiation = attachment of RNA polymerase to promoter and start of synthesis
2) Elongation = RNA strand increases in length, copies DNA sequence
3) Termination = RNA polymerase reaches terminator sequence (Transcription stops, RNA polymerase detaches from RNA molecule & gene, RNA strand is prepared for exportation into cytoplasm)

40
Q

Messenger RNA (mRNA)

A

Transcribes genetic instructions on DNA in the nucleus to ribosomes
- has codons

41
Q

What are the four things that translation requires?

A

1) mRNA, tRNA, rRNA
2) Enzymes
4) Chemical energy in ATP

42
Q

Transfer RNA (tRNA)

A

Interpreter of translation

  • 3 letter words -> amino acids
  • has anticodons
43
Q

What are the functions of tRNA?

A

1) Picking up the appropriate amino acids

2) Recognizing the appropriate codons in the mRNA

44
Q

Anticodon

A

On a tRNA molecule, a specific sequence of 3 nucleotides that is complimentary to a codon triplet on mRNA

45
Q

What does a ribosome consist of?

A

2 subunits, proteins, and rRNA.

46
Q

ribosomal RNA (rRNA)

A

Type of ribonucleic acid that together with proteins make up ribosomes
- most abundant type of RNA

47
Q

What are the differences between the two units? Small and large?

A

Small unit is for binding site of mRNA.

Large unit is for binding site of tRNA.

48
Q

What is the differences between P and A site?

A

P site holds tRNA carrying the growing polypeptide chain.

A site holds tRNA carrying the next amino acid.

49
Q

What is the role of initiation?

A

Determined exactly where translation will begin. It brings together mRNA, first amino acid, tRNA, and 2 subunits.

50
Q

Start codon

A

Specific 3 nucleotide sequences AUG to which an initiator tRNA molecule binds, starting translation of genetic info

51
Q

What are the 3 steps of elongation? (Translation)

A

1) Codon Recognition
- anticodon of incoming tRNA pairs w/ mRNA codon of Site A
2) Polypeptide bond formation
- polypeptide separates from its blinded tRNA and attaches to amino acid carried by tRNA in A site
3) Translocation
- during protein synthesis, the movement of a tRNA molecule carrying a growing polypeptide chain from the A site to P site on ribosome

52
Q

Stop codon

A

in mRNA, one of 3 triplets (UAG, UAA, UGA) that signal gene translation to stop

53
Q

Mutation

A

A change in the nucleotide sequence of RNA; the ultimate source of genetic variety
- base substitution and base insertion/deletion

54
Q

What base substitution?

A

Replacement of 1 nucleotide for another.

  • no, little, or significant change (usually negative)
  • mal alter amino acid w/ little change to function
  • improved proteins/capabilities possible
55
Q

What is base inception/deletion?

A

May alter the reading frame (how nucleotides read 3 nucleotides at a time)
- disastrous effects

56
Q

Mutagenesis

A

Creation of a mutation

  • results from errors during DNA replication/recombination
  • causes… 1) Spontaneous 2) Mutagen
57
Q

Mutagen

A

A chemical or physical agent that interacts with DNA and causes a mutation
- pH, chemical, radiation, etc

58
Q

Lytic cycle

A

A type of viral replication cycle resulting in the release of new viruses by lysis (breaking open) of the host cell

59
Q

Lysogenic cycle

A

A type of bacteriophage replication cycle in which the viral genome is incorporated into the bacterial host chromosome as a prophage
- new phages are not produced, and the host cell is not killed or lysed unless the viral genome leaves the host chromosome

60
Q

Prophage

A

Phage DNA that has inserted by genetic recombination into the DNA of a prokaryotic chromosome

61
Q

How does the virus’s reproductive cycle function?

A

1) RNA enters cytoplasm
2) Enzymes then remove the protein coat
3) Enzymes of virus enters cell to make complementary strands of RNA
4) New coat proteins assemble around the new viral RNA
5) Viruses leave the cell by cloaking themselves in plasma membrane

62
Q

Retrovirus

A

An RNA virus that reproduces by means of a DNA molecule. IT reverse transcribes its RNA into DNA, inserts the DNA into a cellular chromosome, and then transcribes more copies of the RNA from the viral DNA

63
Q

Reverse Transciptase

A

An enzyme that catalyzes the synthesis of DNA on an RNA template

64
Q

AIDS

A

Acquired immune deficiency syndrome; the late stages of HIV infection; characterized by a reduced # of T cells; usually results in death caused by other diseases

65
Q

HIV

A

Human immunodeficiency virus, the retrovirus that attacks the human immune system causes AIDS

66
Q

What is the flow of genetic info?

A

DNA -> RNA -> proteins

67
Q

What does “In genetic code, there is redundancy, by no ambiguity” means what?

A

Some codons code for same amino acid but no codon codes for more amino acids

68
Q

What are introns?

A

Genetic garbage that fills gaps

- majority of strand thought to be used for evolution

69
Q

What are extrons?

A

Sequence that codes for particular protein

70
Q

Primary Transcript

A

First copy of the template

71
Q

What is protein synthesis comprised of?

A

1) Transcription

2) Translation

72
Q

What are the 3 stages of translation?

A

1) Initiation
- When translation begins, binds to smaller subunit
2) Elongation
- Amino acids added to chain, peptide bonds form
3) Termination
- Stop codon reaches A site

73
Q

Tobacco Mosaic

A

Rod Shaped plant virus