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Microbiology > Chapter 7 - Genetics > Flashcards

Chapter 7 - Genetics Flashcards

0
Q

Genome

A
  • entire genetic makeup of an organism

- genes and nucleotides

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1
Q

Genetics

A
  • the study of inheritance and inheritable traits as expressed in an organisms genetic material
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2
Q

Nucleic Acid Structure

A
  • polymers of nucleotides
  • nitrogenous bases bind to each other in DNA through Hydrogen bonds
  • 3prime end has an OH
  • 5prime end has a phosphate
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3
Q

DNA

A
  • genetic material
  • double stranded antiparallel
  • backbone is a deoxyribose ring with 1’ through 5’ carbons
  • 5’ Carbon attaches to the next base’s 3’ Carbon
  • A, T, C, G are nitrogenous bases attached to 1’ Carbon
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4
Q

RNA

A
  • no THYMINE, only Uracil
  • 2’ Carbon contains an OH
  • less stable
  • single stranded
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5
Q

Prokaryotic Chromosomes

A
  • haploid (single copy)
  • one long circular DNA in nucleoid
  • held in place by protein and RNA
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6
Q

Plasmid

A
  • prokaryotic
  • small circular molecules of DNA that are not connected to chromosomes
  • replicate independently of the chromosome
  • don’t contain genes necessary for normal function
  • each cell may have many copies of one plasmid
  • fertility, resistance, bacteriocin, virulence
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7
Q

Nuclear Chromosomes

A
  • Eukaryotic
  • within nucleus
  • more than one chromosome per cell
  • linear
  • diploid (two copies)
  • composed of nucleosomes-chromatin-euchromatin-heterochromatin
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8
Q

Nucleosomes

A
  • when negatively charged DNA wraps around positively charged histones to form beads
  • first step of making a Eukaryotic chromosome
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9
Q

Chromatin

A
  • nucleosomes clumped together with other proteins
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10
Q

Euchromatin

A
  • loosely packed active chromatin
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11
Q

Heterochromatin

A
  • densely packed inactive chromatin
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12
Q

DNA Replication

A
  • DNA becomes new DNA
  • semiconservative, new DNA is composed of 1 original and 1 daughter strand
  • anabolic polymerization process
  • DNA nucleotides carry the energy needed for DNA synthesis (dGTP, dTTP, dATP)
  • bidirectional
  • older strands are METHYLATED (need for DNA repair)
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13
Q

DNA Replication Differences for BOTH

A
  • semiconservative
  • 5’ to 3’
  • primase
  • DNA helicase
  • DNA polymerase
  • Ligase
  • RNAse
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14
Q

DNA Replication Differences for PROK.

A
  • only 1 origin
  • Okasaki fragments are 1000 long
  • occurs in nucleoid
  • all systems continue to work
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15
Q

DNA Replication Differences for EUK.

A
  • many origins
  • Okasaki fragments are about 400 long
  • occurs in Nucleus
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16
Q

Process of DNA Replication

A
  • DNA helicase unwinds DNA so it can be copied
  • replication starts at the origin and spreads both ways (PROK) or has many origins (EUK)
  • a primer is synthesized by primase and binds
  • DNA polymerase binds
  • always goes 5’ to 3’ for new strand (BUT you start at OLD 3’)
  • leading strand is synthesized continuously
  • lagging strand is made in okasaki fragments and glued together by ligase
  • RNAse eats the primer when it is not needed anymore
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17
Q

Genotype

A
  • set of genes in a genome

- series of nucleotides that carry instructions

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18
Q

Phenotype

A
  • physical features and functional traits that can be SEEN
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19
Q

Central Dogma of Genetics

A
  • DNA to RNA = transcription

- RNA to Proteins = translation

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20
Q

Transcription

A
  • DNA to RNA
  • makes RNA primers, mRNA, rRNA, tRNA, Regulatory RNA
  • 3 steps: Initiation, Elongation, Termination
  • need promoter, helicase, RNA polymerase
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21
Q

Transcription Differences in BOTH

A
  • promoter
  • helicase
  • RNA polymerase
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22
Q

Transcription Differences in PROK.

A
  • simple

- occurs in nucleoid

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23
Q

Transcription Differences in EUK.

A
  • occurs in nucleus
  • CAP
  • polyadenylation (AAAAAAAA at the end)
  • splicing
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24
Q

Polyadenylation in Transcription

A
  • Eukaryotes only

- adding 100 to 250 As at the end

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25
Q

Splicing in Transcription

A
  • clipping out the pieces that don’t code for anything (introns)
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26
Q

Intron

A
  • Eukaryotic Transcription

- intervening segments, not used

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27
Q

Extron

A
  • Eukaryotic Transcription

- expressed segments, used

28
Q

Transcription Process

A
  • INITIATION
  • RNA polymerase attaches to DNA and travels down until it recognizes a promoter
  • RNA polymerase then unzips DNA
  • ELONGATION
  • Triphosphate ribonucleotides align opposite their compliments
  • RNA polymerase links the two together and elongates the strand
  • TERMINATION
  • transcription stops
29
Q

Translation

A
  • RNA to proteins
  • use mRNA, tRNA, rRNA, and ribosomes
  • inititation and elongation require energy (GTP)
30
Q

Translation Differences in PROK.

A
  • polycistrone (multiple proteins from the same RNA)
  • translation can start before transcription has finished because it stays in the same place
  • Ribosomes bind at Ribosome Binding Site
  • there can be MANY ribosomes at once
31
Q

Translation Differences in EUK.

A
  • 1 mRNA codes 1 protein
  • RNA must be sent through nuclear pores and caught by cytoplasmic ribosomes
  • Ribosomes bind at 5’ end CAP to start (only one ribosome)
  • Ribosomes can synthesize polypetides in RER through free ribosomes
32
Q

Translation Process

A
  • INITIATION
  • Ribosome binds to the RNA at the RBS (PROK) or at the 5’ end (EUK)
  • the ribosome scans until AUG (start codon)
  • AUG locks into P site of ribosome
  • tRNA recognizes AUG via it’s anticodon
  • the large subunit of the ribosome binds
  • ELONGATION
  • the tRNA that matches the next codon is put into the A site and read
  • rRNA in the ribosome joins the AUG methionine to the 2nd amino acid
  • the ribosome then moves on to the next codon
  • tRNA holding on to the AUG codon moves to the E site and releases
  • TERMINATION
  • this continues until a STOP codon is reached
  • the entire polypeptide chain is released
33
Q

Transfer RNA

A
  • used in Translation
  • 3 leaf clover shaped
  • anticodon on the end that is complimentary to mRNA codon
34
Q

mRNA

A
  • made by Transcription
  • used in Translation
  • what the ribosome reads to create the protein
35
Q

Translation Ribosomes

A
  • Prokaryotic = 70s
  • Eukaryotic = 80s
  • E site = exiting tRNA
  • P site = growing polypeptide, tRNA
  • A site = amino acids
36
Q

STOP CODON

A
  • UAA
  • UAG
  • UGA
37
Q

START CODON

A
  • AUG

- methionine

38
Q

Operon

A
  • prokaryotic
  • consists of a promoter and a group of structural genes
  • controlled by the operator
  • regulatory gene is at a different place completely to turn on/off operon
  • Inducible = catabolic and normally OFF
  • Repressible = anabolic and normally ON
39
Q

Inducible Operon

A
  • catabolic
  • normally OFF, get turned on
  • ex. lactose operon
40
Q

Repressible Operon

A
  • anabolic
  • normally ON, gets deactivated
  • ex. Tryptophan Operon
41
Q

Lac Operon

A
  • inducible operon
  • normally blocked by an inhibitor
  • lactose binds the inhibitor and inactivates it
  • lac operon is turned on
  • cAMP indicates low glucose and stimulates more lac transcription
  • inhibitor is transcribed and attaches to the operator again
42
Q

Tryptophan Operon

A
  • repressible operon
  • on until Trp binds to an inactive repressor in the environment
  • repressor becomes active and binds to operator to block it
43
Q

Mutation

A
  • change in the nucleotide base sequence of a genome
  • almost always bad
  • RNA has more than DNA
  • point => frameshift
44
Q

Point Mutation

A
  • most common
  • one base pair is effected
  • substitutions and frameshifts
45
Q

Substitution Mutation

A
  • point mutations
  • silent = no change in amino acid
  • missense = slightly different amino acid
  • nonsense = creates a STOP codon
46
Q

Frameshift Mutations

A
  • point mutations
  • BAD
  • insertion
  • deletion
47
Q

Mutagens

A
  • physical or chemical agents that cause an increase in mutation rate
  • radiation
  • chemical
48
Q

Radiation Mutagens

A
  • ionizing = xrays or gamma rays

- non ionizing = UV light which causes pyrimidine dimers

49
Q

Chemical Mutagens

A
  • nucleoside analogs
  • nucleotide altering chemicals
  • frameshift mutagens (cause an unreadable bulge)
50
Q

Mutants

A
  • when a mutagen is not removed, it carries on to the daughter cell
  • wild type is the “normal” found in the wild without a mutation
  • to distinguish mutants from wild type, use positive or negative selection
51
Q

Ames Test

A
  • a test to identify mutagen
  • positive selection
  • a strain of Salmonella lacking the ability to synthesize His- is subjected to the mutagen and plated
  • the rate of wild type His- is measured
  • if a higher rate of mutation is seen, this is considered a mutagen
52
Q

Carcinogens

A
  • mutations known to cause cancer
53
Q

Vertical Gene Transfer

A
  • organisms replicate their genomes and provide copies to descendants
  • normal in humans
54
Q

Recombinants

A
  • cells with DNA molecules that contain new pieces of nucleotide sequences
  • basically swapping bits and pieces back and forth
55
Q

Horizontal Gene Transfer

A
  • donor cell contributes part of it’s genome to a recipient in the same generation
  • transformation, transduction, bacterial conjugation
56
Q

Transformation

A
  • horizontal gene transfer
  • bacteria picks up DNA from the environment and uses it as a plasmid or recombination into it’s own DNA
  • plasmids are easier, “ready to use”
  • not many bacteria are competent (can pick up DNA)
  • ex. Griffith and the strepto rats
57
Q

Competent Bacteria

A
  • bacteria that are able to pick up DNA from the environment
58
Q

Transduction

A
  • When a virus infects a cell
  • transducing phage carries random DNA segment from donor to recipient
  • two types: general and specialized
59
Q

Lytic Cycle

A
  • phase in transduction
  • the bateriophage latches onto host cell and injects DNA
  • phage DNA changes cell to make more phage DNA
  • the host cell dies and lyses
60
Q

General Transduction

A
  • bacteriophage attaches to a cell
  • lytic cycle begins
  • some of the host DNA is accidentally packaged into a new bacteriophage
  • this new bacteriophage lands on a new cell, but doesnt enter lytic cycle because the DNA is not bacteria
61
Q

Specialized Transduction

A
  • when a phage is in the lysogenic cycle
  • the insertion point of the bacteria on the cell rips out the host DNA only in that specific spot
  • pulls out only a much more specific sequence
  • ex. Cholera toxin
62
Q

Lysogenic Cycle

A
  • during transduction
  • before lytic cycle
  • the phage injects it’s DNA into the cell
  • phage recombines the host DNA
  • there is a period of waiting until the lytic stage
63
Q

Bacterial Conjugation

A
  • F+ bacteria carry a fertility plasmid that allows them to form a sex pilus
  • The F+ cell attaches to an F- cell to transfer one strand of the F+ plasmid to the F- cell
  • this makes both cells now F+
64
Q

Hfr Conjugation

A
  • type of bacterial conjugation
  • high frequency recombination
  • Hfr cell (F+ plasmid incorporates into DNA) joins an F- cell
  • the F+ plasmid portion is transferred to the recipeint, but because it has become incorporated into the DNA, all the DNA strand gets transferred
  • the sex pilus breaks the cells apart before the transfer is finished and the F- cell ends up with a portion of the Hfr cell
  • the new DNA is recombined with the F- cell and the cell stays F-
65
Q

Transposition

A
  • bits of DNA hopping from one place to another within a genome
  • copying itself, not removing
  • can jump into a plasmid and be sent out of the cell
  • results in a frameshift
66
Q

Transposon

A
  • the segment of DNA that moves from one location to another during Transposition
  • palindromic sequence at either end of segment to help with insertion
67
Q

Simple Transposons

A
  • insertion sequences

- have no more than 2 inverted repeats

68
Q

Complex Transposons

A
  • contain one or more genes not connected with transposition

- most successful

Microbiology (5 decks)

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