Chapter 8 - Microbial Genetics Flashcards

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1
Q

Gene

A

-a segment of DNA
-produces a functional product (usually a protein or an RNA - mRNA, rRNA, tRNA)

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2
Q

Genome

A

-the genetic information in a cell
-includes genes and nucleotide sequences

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3
Q

Chromosomes

A

-structures containing DNA that physically carry hereditary information
-contain the genes

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4
Q

DNA

A

-macromolecule comprised of repeating units call nucleotides (GCAT)

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5
Q

Antiparallel Nature of DNA

A

-the sugar in one strand is upside down
-creates stability (hydrogen bonds)
-allows the bases to remain close together

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6
Q

Leading Strand

A

-Carbon #5 is at the top and is in line with carbon #3 at the bottom
-synthesized continuously in the same direction

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7
Q

Lagging strand

A

-Carbon #3 is at the top and carbon #5 is in line with it at the bottom
-synthesized discontinuously in fragments of about 1000 nucleotides

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8
Q

Okazaki Fragments

A

-lagging strand
-the discontinuously synthesized fragments that are later joined to make a continuous strand

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9
Q

Genetic Code

A

-set of rules that determines how a nucleotide sequence is converted to the amino acid sequence

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10
Q

Importance of Complementary Base Pairs

A
  1. linear sequence provides information
  2. allows for DNA replication during cell division
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11
Q

Genotype

A

-genetic makeup of an organism

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12
Q

Phenotype

A

-actual, expressed properties

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13
Q

Central Dogma of DNA

A

-describes how DNA is transcribed into mRNA
-mRNA is in turn translated into proteins that carry out functions

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14
Q

Base Substitution Mutations

A

-single DNA base pair is altered

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15
Q

Frameshift Mutations

A

-DNA base pairs are added or removed from sequence causing a shift in the reading

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16
Q

DNA Replication

A

-one double stranded DNA molecule is converted to two identical offspring molecules

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17
Q

Semiconservative Replication

A

-consists of an original strand and a newly synthesized daughter strand

18
Q

DNA Polymerase

A

-enzyme that joins the nucleotide to the DNA strand in DNA replication
-adds nucleotides to hydroxyl group at the 3’ end of each nucleic acid

19
Q

DNA Replication Steps

A
  1. parental DNA double helix separates, hydrogen bonds break in response to enzyme action
  2. hydrogen bonds form between new complementary nucleotides, forming new base pairs
  3. enzymes catalyze the formation of sugar-phosphate bonds on each resulting daughter strand
20
Q

Energy Needs

A

-DNA replication requires a great deal of energy

21
Q

Step 1: Unzipping (DNA Replication Fork)

A

-enzyme DNA Helicase unwinds the parental double helix

22
Q

Step 2: Stabilization (DNA Replication Fork)

A

-enzyme DNA gyrase stabilizes the unwound parental DNA
-relieves tension
-forms the replication fork (steps 3 and 4)

23
Q

Step 3: Leading Strand (DNA Replication Fork)

A

-Enzyme DNA Polymerase is synthesized continuously from the primer
-the proof reader
-used ATP
-results in 5’→3’ (old) and then forms 3’→5’ (new)

24
Q

Step 4: Lagging Strand (DNA Replication Fork)

A

-synthesized discontinuously
-Enzyme RNA polymerase (Primase) synthesizes a short RNA primer which is extended by DNA polymerase
-helps DNA polymerase add new nucleotides

25
Q

Step 5: After step 4 (DNA Replication Fork)

A

-DNA polymerase digests RNA primer and replaces it with DNA
-Okazaki fragments
-leave a gap

26
Q

Step 6: Follows step 5 (DNA Replication Fork)

A

-the gaps are sealed
-DNA ligase joins the discontinuous fragments of the lagging strand
-results in 5’→3’ (old) and then forms 3’→5’ (new)

27
Q

Bacteria Replication

A

-replication of DNA is quicker and this allows colonies to appear quickly
-replication moves bidirectionally around the chromosome
-the replication forks meet when replication is completed

28
Q

Transcription

A

-copying
-the template to make RNA
-info in DNA is copied as a RNA nucleotide sequence

29
Q

Translation

A

-cell uses encoded RNA info to make specific proteins
-decoding the language of nucleic acids converting it to the language of proteins

30
Q

Ribosomal RNA

A

-cellular machinery for protein synthesis
-larger in eukaryotes

31
Q

Messenger RNA

A

-carries the coded information for making proteins from DNA to ribosomes
-the codon = 3 nucleotides

32
Q

Transfer RNA

A

-“box car”
-brings the amino acid to the site of protein synthesis

33
Q

Ribosomes

A

-where proteins are synthesized

34
Q

Prokaryotes

A

-DNA replication occurs in cytoplasm
-there is no nuclear envelope

35
Q

Eukaryotes

A

-DNA replication occurs in the nucleus
-involves RNA splicing

36
Q

RNA Splicing

A

-mRNA is processed before translation
-alternating exons (good regions) and introns, introns are removed and exons are left
-the exon chain travels to the cytoplasm where it directs protein synthesis

37
Q

Steps in Transcription

A
  1. RNA polymerase binds to the promotes, DNA unwinds at the beginning of the gene
  2. RNA is synthesized by complementary base pairing with bases on the template DNA strand
  3. site of synthesis moves along the DNA, transcribed DNA rewinds
  4. transcription reaches the terminator
  5. RNA and RNA polymerase are released and the DNA helix reforms
38
Q

mRNA Vaccine

A

-a copied gene froma virus
-won’t affect your genetics
-decoded viral gene

39
Q

Exons

A

-regions of DNA that are expressed

40
Q

Introns

A

-intervening regions of DNA that do not encode protein

41
Q

Steps in Translation

A
  1. the components needing to begin translation come together
  2. tRNA carrying the first aa is paired with the start codon on the mRNA, tRNA carrying second aa approaches
  3. second codon of mRNA pairs with tRNA carrying second aa, first aa joins the second via a peptide bond
  4. ribosome moves along the mRNA
  5. second aa joins the third by another peptide bond and the first tRNA is released
  6. ribosome continues to move along the mRNA and new aa’s are added to the polypeptide chain
  7. when ribosome reaches a stop codon, the polypeptide is released
  8. tRNA is released and the ribosome comes apart, released polypeptide forms a new protein