Chapter 8 Flashcards
Importance of genetics
Understand cell function Evolution of species Advancement in agriculture Understand diseases Info on antibiotic resistance
What is genetics
Study of function and transfer of genes
What is genome?
ALL genetic info in cell
Contain chromosomes
How many chromosomes E.coli have?
How many genes?
How long is stretched out?
1 chromosome
4288 genes
Stretch 1mm if unwound
How many chromosomes do humans have?
Stretches??
46 chromosome
6 feet
What are chromosomes?
Contain genes
What are genes?
DNA segments
What are three types of genes?
Structural: code for protein
Regulatory: control gene expression
Genes that code for RNA
*structural most important
What are genetic code
Set of rules that determine how nucleotides sequence is converted into a protein
What is genotype?
Genetic make up
Represents potential characteristics
Ex. Serratia marcescens COULD turn red
Phenotype
Expression of genotypes
Actual observable characteristics
Ex. Serratia marcescens is red
What does DNA stand for
Deoxyribo Nucleic Acid
What are the component of Nucleic acid?
Nucleotides
What are the three nucleotides component?
5 carbon sugar
Phosphate
Nitrogenous base
What are the nitrogenous bases?
Adenine
Thymine
Cytosine
Guanine
What is complementary base pairing
Certain nucleotides bases pair together
A-T
G-C
What kind of bonds are between bases?
Hydrogen bonds
Each DNA molecule has
2 strands of nucleotides
Strained in DNA molecule are
Antiparallel 5’ –> 3’ and 3’ –> 5’
Carbon of dexoxyribose are numbered
1’ through 5’
5’ end _______ add nucleotides(P)
Cannot
3’ end _______ add nucleotides (OH)
Can
Flow of genetic information
DNA ————–> mRNA –> protein
^(Transcription). ^translation
DNA ————–> mRNA –> protein
^(Transcription). ^translation
Is called
Central dogma
what is genotype?
genetic make up
represent only potential charactersistics
ex. Serratia macescen COULD turn red
what are the steps of DNA replication?
- double helix is seperated by helicase
- replication fork forms at origin of replication
- leading strand is synthesized continously as DNA polymerase add new nucleotides (5’ to 3’)
- Lagging strand uses RNA primer to lay down short pieces of RNA
- On lagging strand, DNA polymerase removed RNA primer and replaces it with DNA
- On lagging strand DNA ligase joins fragments of DNA
- DNA polymerase proofreads to ensure proper base pairing occurs
how is the lagging strand formed?
synthesized in pieces because there is no free 3’ end
helicase
enzyme that unwinds double helix
template
original strand of DNA
where 2 strands are seperated and new nucleotides are added
replication fork
enzymes that add new nucleotides and proof reads
DNA polymerase
Small pieces of RNA where DNA polymerase can attach
RNA primer
enzyme that joins fragment of DNA (glue) on lagging strand
DNA ligase
Pieces of RNA fromed on teh lagging stand
OKAZAKI fragment
transcription
process of making mRNA from a DNA template
what is the end result of transcription?
mRNA
what does mRNA do:
carries infromation transcribed from DNA
contains codons
what does tRNA do?
carries amino acids
contains anticodons which pair with codons on mRNA
what does RNA polymerase?
Enzyme that make new strand of mRNA
what is the promotor?
Site on DNA template where RNA binds
what is the terminator?
site on DNA template that end transcription
what are the steps in transcription?
- RNA polymerase binds to promotor site on the DNA template
- RNA polmymerase synthesizes a complementary base strand of DNA template working in a 5’ to 3’ direction
- transcription continues until a terminator is reached
- RNA polymerase and new mRNA are released from DNA
what is translation?
process of protein synthesis
What is the end product of translation?
protien(enzyme)
how are ribosomes involved in translation?
site of translation attaches to mRNA
contains two sub units
30s and 50s
contians 3 tRNA binding sites
tRNA binding sites are?
A
P
E
What tRNA A site?
acceptor; hold tRNA carries the next amino acid
what is tRNA P site?
peptide; holds tRNA with growing peptide chain
what is tRNA E site?
exit
what are the steps in translation
intitiation
elogation
termination
what are the steps in initiation?
- start condon, AUG, signals mRNA to bind to sm. subunits of ribosomes
- initate tRNA ( with amino acid met.) attaches its anticodon (UAC) to mRNA in P site of ribosome
- Large and small subunits of ribosome join
what are the steps in elongation?
- mRNA is threaded through ribosome
- 2nd tRNA with amino acid binds it anticodon with mRNA’s codon A site of ribosome
- peptide bond form between amino acid
- polypeptide chain is transfered to tRNA in A site and 1st t RNA moves to the E site and is released
- tRNA with growing peptide chain moves A to P
what are the steps to termination?
- elongation. continues until a stop codon is reached at A site
- Ribosome split apart polypeptide chain
* protien fold and becomes funtional*
what is a codon?
set of 3 nucleotides based mRNA that encodes for specific amino acid
64 possible codons and 20 amino acids
61 are sense codons
3 are nonsense codons
what are sense codons?
amino acids
what are nonsense codons?
UAG, UAA , and UGA
what is the regulation of gene expression?
most metabolic reaction are catalyzed by enzymes(protein)
cells only produce enzymes when they are needed and only perform needed chemical reaction
cell control activity by feedback inhibition
the process to make enzyme are controled by genetics; transcription and translation
genes that code fro enzymes that are needed most of the time say on all the time
genes that code for enzymes that are only need at certain times are regulated
what is feedback inhibiton?
inhibition of enzymes when reaction is unnecessary
what is the repression of genes?
process that turns off transcription
caused by over production of end product from metabolism
repressors block RNA polymerase at promotor
induction
the relief of repression for a gene or set of genes under negative control repressor
what is operon
system of gene regulation includes genes,promotor or operon
what is a promotor
where RNA polymerase starts transcription
what is operator?
start/stops transcription of lac gene
E. coli with lac gene
E. coli contains an inducibe systems for lactose metabolism
lac operon’s job is to regulate what/
the lac. gene and there for regulate transcroption and translation
lac operon under normal conditions is
turned off when glucose is present
when lactose is present lac operon must
broken down by beta-galactosidase
what does beta-galactosidase do”
splits lactose–> glucosa and galactose
what does glucose and galactose do/
are used by E. coli in metabolism to make ATP
when the lac operon is on in E. coli in medium with lactose
- lactose is transported into cell and converted to allolactose (inducer)
- allolacotose binds to repressor (turn off) which turns on genes for RNA polymerase to transcibe mRNA
- mRNA is translated and beta-galacosidase is produced
E. coli in medium without lactose operons is off
- repressor active is bound to operator
- mRNA is Not transcribed
- Translatino do NOT occur
- beta-galactosidase is NOT produced
what are mutation?
changes in base sequence of DNA
are permenant and passed to next generation
can help with environmental changes(natural selection)
ex. antibiotic resistance
what are base substitution?
single base in released with another base
missense mutation?
base substitution results amino acid substitution
nonsense mutation?
base substituition codes for nonsense codon
what is frameshift mutation?
one or more bases are deleted or inserted
what are mutagens?
substance that cause mutaion
what are the different types of mutagens?
chemicals – nitrate and nitrite –household cleaners
radiation– UV light and X-ray– causes pyridine dimer (thymine) to form
what is genetic transfer?
exchange of genes between 2 DNA molecule to form new combination of genes
what are genetic cross over?
2 chromosome break apart and rejoin
results ; 2 original chromosomes have combination of each other
what is cross over important?
genetic recombination contributes to a population’s genetic diversity
genes for resistance to drug and metabolic poison develop
new nutrional and metabolic capacities develop
increase virulence
what are plasmids?
circular pieces of DNA
replicated seperately from chromosomal DNA
can enhance pathogenicity
what are the three genetic transfer?
- transfromation
- conjugation
- translation
what is transformation?
process of genetic transfer when a cell lyse and “naked’ DNA is transfered to another bacteria
how does transforation work?
donor DNA combine with recipeint DNA form a new recombinant (if closely related)
occur in Bacilus and Streptococcus, and Staphylococcus
What is plasmid F factor?
used in conjugation
carres gene for sex pillus
what is plasmid R factor?
plasmid that transfered antibiotic resistance
transfer multiple resistance to antibiotic (tetracycline, chloramphenicol, stretomycin, sulfonamide, and penicillin)
synthesize factor such as toxin, enzymes adhesion
can transfer resistance to heavy metal
what is conjuagation in bacteria?
process of genetic transfer that involves sexual mating using a plasmid
require cell to cell contact
must be oppiosate mating type
what are the components involved in conjugation?
sex pilus: connection Donor: has plasmid F+ Recipeient: no plasmid F-
what are the steps in conjuation?
- sex pilus grows out F+ and attahes to F- cell
- copy of F+ is transfered to recipient F0
result is F+ + F- = F+ + F+
what is the transduction?
process of genetic transfer in which DNA is passed from one bacterium to another by a bacteriphage
what are the steps in transduction?
- bacteriphage attaches to a bacterium and injects its DNA
- bacteriophage breaks down bacterium’s DNA
- bacteriphage replicates self and part of original bacterium’s DNA is packed in new bacteriophage
- bacteriophage lyse bacteria and infect other bacteria
- new bacteriphages land a new bacteria and DNA of the two bacteria and combined
what are transpons?
segments of DNA that move from 1 region to antoher
“jumping genes”
what are the advantages of transpons?
creation of genetic diversity
change in traits such as pigmentation and morphology
replacement of damaged DNA
what are the disadvantages of transpons?
can lead to mutation
can cause cell dysfunction
