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Genetics
DNA
46
Microbiology
Undergraduate 1
11/09/2010

Additional Microbiology Flashcards

 


 

Cards

Term
Heredity
Definition
the transmission of genetic information from an organism to its progeny (offspring).
Term
Chromosomes
Definition
a circular (prokaryotes) or linear (eukaryotes) molecule of DNA and proteins that contains genes
Term

DNA structure

Definition
arranged in a double helix
contains deoxyribose sugar and phosphate backbone
composed of nucleotides (A, T, C, G)
Antiparallel strand orientation
Strands are complementary
Term
nucleotides
Definition

DNA- ATCG

RNA-AUCG

Term

Genes

Definition
a segment of DNA specifying a particular product (usually a protein)
Term

Alleles

Definition
 different variations of the same gene
Term
Mutation
Definition
permanent alteration in DNA
Term

 

Genetic information transfer

 

Definition

 the Central Dogma of molecular biology

[image]

Term
Replication
Definition
DNA synthesis; existing DNA used as a template to make new DNA
Term

 

Transcription

 

Definition
RNA synthesis; existing DNA (genes) used as a template to make RNA (rRNA, mRNA, and tRNA).
Term
Translation
Definition
Protein synthesis; RNA molecules are used to form proteins from amino acids
Term
What Direction does DNA replication take place?
Definition
Always occurs in a 5’ to 3’ direction
Term
What direction does the two replication forks move?
Definition
Bidirectionally (progress in two directions simutaneously)
Term
What are required enzymes for DNA replication?
Definition

Gyrase
Helicase
DNA polymerase
Ligase

Term

 

Gyrase

 

Definition
 unwinds the DNA double helix.
Term

Helicase

Definition
“unzips” the two strands of DNA (breaking of hydrogen bonds that hold the strands together).
Term
DNA polymerase
Definition
adds nucleotides to synthesize a new DNA strand (daughter strand) from the template strand (parental strand)
Term

Ligase

Definition
 seals the “nick” where replication forks meet (adds the final phosphodiester bond).
Term

 

Leading strand synthesis
Definition
replication is continuous because the replication fork is already moving in a 5’ à 3’ direction for the leading strand.
Term

Lagging strand synthesis

Definition
 replication is discontinuous (via the synthesis of Okazaki fragments) because the replication fork is moving in a 3’ à 5’ direction for the lagging strand, which does not work for DNA polymerase.
Term

RNA Synthesis- Transcription is catalyzed by this

Definition

 

RNA Polymerase
Term

Promoter sequences

Definition
site on a gene where RNA polymerase binds and begins transcription
Term

3 RNA types

Definition

 

ribosomal RNA (rRNA)
messenger RNA (mRNA)

transfer RNA (tRNA)
Term

ribosomal RNA (rRNA): 

Definition
component of ribosomes
Term

messenger RNA (mRNA)

Definition
template for protein synthesis
Term

transfer RNA (tRNA)

Definition
brings amino acids to the ribosome for the growing polypeptide
Term

 

Eukaryotic

 

Definition
genes contain introns that are excised
RNA synthesis in nucleus; protein synthesis in cytoplasm
Term

Prokaryotic

Definition
no introns in genes
RNA and protein are synthesized in the cytoplasm
Term

mRNA codons

Definition
determine the amino acid sequence of a protein.
Term

tRNA anticodons – 

Definition
complementary to the codons of mRNA
Term

A tRNA carrying an amino acid 

Definition
is “charged”. An uncharged tRNA is not bound to an amino acid.
Term

rRNA 

Definition
component of ribosomes, which catalyze protein synthesis.
Term

Ribosomes: Small

Definition

(30S) subunit

composed of 16S rRNA and 21 proteins
Term
Ribosomes Large
Definition
(50S) subunit
composed of 5S rRNA, 23S rRNA, and 31 proteins
Term

Enzyme Repression  

Definition
enzymes to metabolize a substrate are not made if the substrate is not present 
Term

Enzyme Induction 

Definition
– enzymes to metabolize a substrate are made if the substrate is present.
Term

Point mutations

Definition
Missense

Nonsense

Silent
Term

Missense

Definition
base change results in a new codon that dictates a different amino acid.
Term

Nonsense

Definition
: base change results in a stop codon that terminates translation.
Term

 

Silent
Definition
: base change results in a new codon that does not change the amino acid.
Term

 

Frameshift
Definition
caused by the deletion (–1)  or insertion (+1) of a base.
Term
Causes of DNA mutations
Definition

Spontaneous errors during DNA replication

Chemical mutagens
base analogs – mimic nitrogenous bases
acridine derivatives – cause frameshifts

 

UV Radiation
causes thymine dimers
Term
Start Codon
Definition
AUG
Term
Stop Codon
Definition

UAA

UAG
UGA

Term
Name three types of rRNA
Definition

16S

23S

5S

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