Chapter 8 - Microbial Genetics

Question 1

Gene

Answer 1

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

Question 2

Genome

Answer 2

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

Question 3

Chromosomes

Answer 3

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

Question 4

DNA

Answer 4

-macromolecule comprised of repeating units call nucleotides (GCAT)

Question 5

Antiparallel Nature of DNA

Answer 5

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

Question 6

Leading Strand

Answer 6

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

Question 7

Lagging strand

Answer 7

-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

Question 8

Okazaki Fragments

Answer 8

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

Question 9

Genetic Code

Answer 9

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

Question 10

Importance of Complementary Base Pairs

Answer 10

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

Question 11

Genotype

Answer 11

-genetic makeup of an organism

Question 12

Phenotype

Answer 12

-actual, expressed properties

Question 13

Central Dogma of DNA

Answer 13

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

Question 14

Base Substitution Mutations

Answer 14

-single DNA base pair is altered

Question 15

Frameshift Mutations

Answer 15

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

Question 16

DNA Replication

Answer 16

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

Question 17

Semiconservative Replication

Answer 17

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

Question 18

DNA Polymerase

Answer 18

-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

Question 19

DNA Replication Steps

Answer 19

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

Question 20

Energy Needs

Answer 20

-DNA replication requires a great deal of energy

Question 21

Step 1: Unzipping (DNA Replication Fork)

Answer 21

-enzyme DNA Helicase unwinds the parental double helix

Question 22

Step 2: Stabilization (DNA Replication Fork)

Answer 22

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

Question 23

Step 3: Leading Strand (DNA Replication Fork)

Answer 23

-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)

Question 24

Step 4: Lagging Strand (DNA Replication Fork)

Answer 24

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

Question 25

Step 5: After step 4 (DNA Replication Fork)

Answer 25

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

Question 26

Step 6: Follows step 5 (DNA Replication Fork)

Answer 26

-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)

Question 27

Bacteria Replication

Answer 27

-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

Question 28

Transcription

Answer 28

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

Question 29

Translation

Answer 29

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

Question 30

Ribosomal RNA

Answer 30

-cellular machinery for protein synthesis -larger in eukaryotes

Question 31

Messenger RNA

Answer 31

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

Question 32

Transfer RNA

Answer 32

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

Question 33

Ribosomes

Answer 33

-where proteins are synthesized

Question 34

Prokaryotes

Answer 34

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

Question 35

Eukaryotes

Answer 35

-DNA replication occurs in the nucleus -involves RNA splicing

Question 36

RNA Splicing

Answer 36

-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

Question 37

Steps in Transcription

Answer 37

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

Question 38

mRNA Vaccine

Answer 38

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

Question 39

Exons

Answer 39

-regions of DNA that are expressed

Question 40

Introns

Answer 40

-intervening regions of DNA that do not encode protein

Question 41

Steps in Translation

Answer 41

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