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Sum total of genetic material of a cell (chromosomes + mitochondria/chloroplasts and/or plasmids
Genome
Genome of cells
DNA
Genome of viruses
DNA or RNA
DNA complexed with protein constitutes the genetic material as ______
Chromosomes
Describe bacterial chromosomes
Single circular loop
Describe eukaryotic chromosomes
multiple and linear
What is a chromosome subdivided into
Genes
The fundamental unit of heredity responsible for a given trait
gene
site on the chromosome that provides information for a certain cell function
Gene
Segment of DNA that contains the necessary code to make a protein or RNA molecule
gene
Three basic categories of genes
Genes that code for proteins
Genes that code for RNA
Genes that control gene expression
Genes that code for proteins
Structural genes
What are most genes considered
Structural genes
Genes that control gene expression
Regulatory genes
True or false: genomes vary in size
True
Smallest virus contains how many genes
4-5 genes
Describe E.coli genome
Single chromosome containing 4,288 genes; 1mm; 1,000X longer than cell
Describe human genome
46 chromosomes containing 31,000 genes; 6 ft; 180,000 X longer than cell
How many origins of replication do bacteria have?
one
Nucleotides of Ribonucleic Acid (RNA)
- Sugar: ribose
- phosphate
- base
Nucleotides of Deoxyribonucleic Acid (DNA)
- sugar: deoxyribose
- phosphate
- base
How to spot the difference between DNA and RNA
-different sugars
- 2' OH in ribose
- 2' H in deoxyribose
Where is the only place DNA polymerase can attach nucleotides
Growing point at 3' OH
Polymerization
Growth ( joining of monomers to form a polymer)
How are the two strands of DNA arranged
Antiparallel
Purines and pyrimidines are
The "base" component of a nucleotide
Purines
Adenine and Guanine
Which bases have a double ring
Purine
Which bases have a single ring
Pyrimidine
What end of a DNA or RNA molecule is the growing end?
3' end
The amount of _____= the amount of ______
Adenine= thymine
Cytosine= guanine
How many bonds between C and G
Three
How many bonds between A and T
Two
DNA secondary structure consists of
Double helix
True or false: DNA supercooling occurs in only bacterial DNA
False: all DNA
The "central dogma"
Replication of DNA
Transcription into RNA
Translated into protein
The genes that contribute to a particular phenotype
Genotype
The observable traits or characteristics that result from genes
Phenotype
What are the three processes involved in information transfer in the cell
Replication, Transcription, and translation
Describe DNA replication
Semiconservative- one old strand and one new strand
Replication of the bacterial chromosome
- one origin of replication
- bidirectional
- dual replication forks
- leading and lagging strand synthesis
DNA replication steps
- synthesis takes place simultaneously but in opposite directions on the two DNA template strands
- DNA replication at a single replication fork begins when a double-stranded DNA molecule unwinds to provide two single-strand templates
Short fragments of DNA produced by discontinuous synthesis
Okazaki fragments
Which strand produces Okazaki fragments
lagging strand
The DNA "replisome"
1. Chromosome unwound by helicase forming replication fork
2. DNA Poly III adds nucleotides adds to leading and lagging strands
3. Lagging strand synthesis must have RNA primer laid down before replicating
4. DNA poly I removes RNA primers and fills in gap
5. Ligase connects unjointed ends of nucleotides (a nick)
Leading strand synthesis
Towards the replication fork
Template for leading strand
3' to 5'
template for lagging strand
5'-3'
Why must the lagging strand of DNA be replicated in short pieces
DNA polymerase III can only synthesize in one direction
Which strand of DNA grows continuously towards the fork
Leading strand
What happens if a mismatch in base pairing during replication occurs
DNA Poly III has proofreading ability to cut out mismatches nucleotide and insert the correct base
Where does RNA polymerase bind to initiate transcription
Promoter region
One gene forms
One protein
Transcription
RNA polymerase moves along DNA template, synthesizing mRNA in the 5' to 3' direction and unwinds and rewinds DNA
Is information processing more complex in prokaryotes or eukaryotes
Eukaryotes
_____ are excised during processing
Introns
Where does replication and transcription occur in eukaryotes
Nucleus
Where does translation occur in eukaryotes
cytoplasm
Where does replication occur in prokaryotes
cytoplasm
Where does transcription occur in prokaryotes
cytoplasm
Where does translation occur in prokaryotes
cytoplasm
The master genetic code
Represented by the mRNA codons and the amino acids they specify
Code is universal among organisms
Code is redundant
What does it mean to say the genetic code is redundant
More than one codon can specify the addition of the same amino acid. (Protects from mutations)
What does every protein start with
AUG (Met)
What does every protein end with
Stop codon
What structure contains the anticodon during translation
TRNA
Where does translation occur
ribosome
______ and _______ occur simultaneously in prokaryotes
Transcription and translation
What happens during elongation during translation
Ribosome attaches at 5' end of transcript
Which strand is transcribed
Template
Which strand during replication has the 5' end towards the replication fork
Lagging strand
Which strand has 3' end and can grow continuously towards the replication fork
Leading strand
A theta structure is formed during which process
Replication
Three levels at which enzymes can be refulated
At transcription, at translation, or _____
In prokaryotes, expression is generally regulated at the level of ______
Transcription
In bacteria and archaea, genes are usually organized into what
Operons
A cluster of genes whose expression is controlled by a single operator
Operon
a specific region of the DNA at the initial end of a gene or operon, where a repressor protein binds and blocks mRNA synthesis
operator
A regulatory protein that binds to specific sites on DNA and blocks transcription
repressor protein
When a drug is used to control an infection, the practice is termed
Antimicrobial chemotherapy
A class of compounds which inhibit or kill microorganisms
Antimicrobial drugs
Natural antimicrobial drugs
Antibiotics
Man-made microbials
Synthetics
Antibiotics which have been chemically modified
semisynthetics
Target a wide variety of pathogenic bacteria
Broad spectrum agents
Target only a narrow subset of pathogens
Narrow spectrum agents
Who discovered penicillin
Alexander Fleming
Main sources of useful antibiotics
Streptomyces and Bacillus (bacteria), Penicillium and Cephalosporium (fungi)
True or false: thousands of antimicrobials have been discovered but relatively few of these are useful
True
Why cant penicillin be toxic to human cells
We dont have peptidoglycan and bacteria do
The main trick if one were to design an antibiotic
find something the target pathogen has or does (e.g. a structure or pathway) which the host cell doesn't
True or false: most bacteria have peptidoglycan while eukaryotes dont so a compound which destroys or inhibits its production (like penicillin) shouldn't affect eukaryotes
True
True or false: toxicity to the host is a major concern of antimicrobials
True
What is therapeutic index
ratio of a drug's toxic dose to its minimum therapeutic dose
5 main approaches of antimicrobials
Inhibition of cell wall formation
Inhibition of cell membrane function (less common)
Inhibition of DNA synthesis
Inhibition of ribosomes/protein synthesis
Inhibition of metabolic pathways
Which antimicrobial inhibit cell wall formation
Penicillins and cephalosporins (beta lactam antibiotics)
What antimicrobial inhibits cell membrane function
Polymixin
Which antimicrobial inhibits DNA synthesis
Ciprofloxacin
Which antimicrobials inhibit ribosomes/protein synthesis
Tetracyclines and erythromycin
Which antimicrobials inhibit metabolic pathways
Sulfa drugs