Microbial Genetics

Question 0

Genome

Answer 0

• all genes in an organism
• most are associated with the chromosome
• extra chromosomal genes
  In prokaryote: plasmids
  In eukaryotes: mitochondria, chloroplasts, and plasmids in some one called organisms

Question 1

Gene

Answer 1

A section of DNA that codes for a protein

Question 2

Telomeres

Answer 2

• ends of linear chromosomes

- when they are frayed and worn, linked with aging and chronic diseases

Question 3

Nucleotide

Answer 3

Building blocks for nucleic acids

• attachment- prime 1- nitrogen base
• attachment- prime 3- hydroxyl group
• attachment- prime 5- phosphate group

Question 4

Purine

Answer 4

2 ring structure

Ex: Adenine , Guanine

Question 5

Pyrimidines

Answer 5

1 ring structure

Ex: thymine, cytosine

In RNA- Uracil, Adenine

Question 6

Complimentary Base Pairs

Answer 6

Pyrimidine and Purine

DNA- double stranded helix
Thymine, Adenine
Cytosine, Guanine

Question 7

DNA Replication

Answer 7

Precursor for cells dividing( mitosis= interphase)

Question 8

Antiparallel concept

Answer 8

Applies to DNA molecules

DNA always grow 5’~3’

Question 9

DNA Replication- Leading Strand

Answer 9

1. Helicase- help break down hydrogen bonds between complimentary bases.( unzips)
2. Leading strand- always starts with RNA primer
   (piece of RNA)- Primase-RNA Polymerase
3. DNA nucleotides are going to attach to RNA primer and continue to grow 5’~3’-grows continuously DNA polymerase 3 does this
4. RNA primer is removed by DNA polymerase 1

Question 10

DNA Replication- Lagging Strand

Answer 10

1. Grows in fragments called Okazaki Fragments
   each fragment grow 5’~ 3’
2. Each fragment start with RNA primer( enzyme RNA polymerase)
3. DNA nucleotides are built onto RNA primer( DNA polymerase 3)
4. RNA primer removed ( DNA polymerase 1)
5. DNA ligase attaches DNA fragments ( Okazaki fragments)

Gyrase- super coils DNA

Question 11

Genetic Code

Answer 11

• based on triplets of DNA nucleotides
• plenty to cover the 20 aa used to make proteins
• each triple codes for an aa and or punctuation- where it start and stop

Question 12

Transcription

Answer 12

• mRNA makes a complementary copy of DNA
• in euk- nucleus
• in prok- cytosol

Question 13

Translation

Answer 13

• protein synthesis
• mRNA attaches to the ribosome and t- RNA brings in raw aa
• Codon- triplets in nucleotide in mRNA only
• Anticodon- triplets in nucleotide in tRNA only

Question 14

Types of RNA

Answer 14

• mRNA- important in both transcription and translation

- tRNA- important in translation only; brings in aa to ribosomes as needed

Question 15

Differences in Eukaryotes and Prokaryote

Answer 15

• eukaryotes- transcription and translation are separate events. Why? Nucleus have nuclear membrane
• prokaryote- transcription and translation can happen on mRNA

Question 16

Exon

Answer 16

Expressed; needed “code”

Question 17

Intron

Answer 17

Are not expressed “ cut out “

Question 18

5th RNA

Answer 18

Works as enzyme, cuts out intron, splices exons together

Question 19

Operon

Answer 19

Control enzymes and different products

Prokaryote

Question 20

Regulatory genes

Answer 20

• codes for repressor protein that can fit on the operator gene and block transcription of the structural genes
• can be anywhere on the chromosome
• code for a protein that blocks operator

Question 21

Operon

Answer 21

• Have to be found together on a chromosome

- promotor gene, operator gene, structural gene

Question 22

Promoter Gene

Answer 22

• Consists of a palindrome of nucleotide bases that signals the beginning of a codon
• palindrome- a santa at NASA/ DNA Land
• signals start

Question 23

Operator Gene

Answer 23

• works as a red/ green light
• if blocked nothing happens
• if not blocked transcribed and then translated into protein

Question 24

Structural Gene

Answer 24

• code for specific enzymes that help in catabolic or anabolic reactions
• if operator gene is not blocked, the structural genes are transcribed, translated, and cell can now metabolize something

Question 25

Two Different Operons

Answer 25

• inducible operons- are normally off, but can be turned on
• they normally are involved in catabolism

Ex: lac operon

• Repressible Operons- are normally on, but can be turned off, normally by excess product
• normally are involved in anabolism

Ex: trp Operons

Question 26

Lac Operon

Answer 26

• control lactose digestion

Question 27

Trp operon

Answer 27

• aa

Question 28

Point Mutations

Answer 28

• one nucleotide is changed
• SNPs “snips”- single nucleotide polymorphisms
• silent mutations- 1nucleotide changes and codes for the same aa
• missense mutations-1 nucleotide changes, codes for diff. aa
• Nonsense mutation- 1 nucleotide changes, code for stop codon

Question 29

Frameshift mutations

Answer 29

• the whole reading frame shifts due to an addition or deletion

Question 30

Factors that increase Mutations

Answer 30

• radiation
• heat
• high dose of electricity
• extremes in ph
• some caustic chemicals

Question 31

Chemical Factors

Answer 31

• benzopyrenes- produced from burned products
  Frameshift mutagens
• Alfa toxins- from aspergillus mold
  Frameshift mutagens
• base analogs- imitate nitrogen bases

Question 32

Genetic Transfer

Answer 32

Conjugation

           - bacterial sex
           - f+ plasmid poke f- plasmid to make it fit

Question 33

Genetic transfer ( Transformation)

Answer 33

• bacteria pick up pieces of DNA or plasmids from the environment, and incorporate this into their genome
• griffiths experiment
• bacteria picks up DNA outside of cell

Question 34

Genetic transfer ( Transduction)

Answer 34

• genes are transferred accidentally by a bacteriophage

- species specific transfer