Microbial Genes Flashcards
Genetics
how organisms inherit information from their parents
Genome
sum of all the genetic material for the cell
What does the genome include?
chromosomes, plasmids (bacteria and fungi cells), DNA in organelle (eukaryotes; mitochondria and chloroplasts), chromosome DNA (this is always included)
What is the difference between prokaryotic DNA and eukaryotic DNA?
there is more DNA in eukaryotes and the DNA is much longer
When the cell divides the DNA become shorter. How does the cell make sure that essential DNA is kept whenever DNA is cut off?
telomeres are added to the ends of the DNA
How do the cells combat the difficulties of replication DNA?
eukaryotic genes have more than one origin of replication to increase the speed
Why is eukaryotic DNA hard to replicate?
e longer length of the DNA, it takes longer to synthesize/copy and the DNA is linear
Telomeres
repetitive sequences that have no significance to the organisms and wont affect it that are cut off during replication
Telomerase
enzyme which makes the telomeres longer
How are telomeres affected by age of the cell?
the older the cell the shorter the telomeres
When does gene expression occur in a cell?
all the time
What two process does gene expression undergo?
transcription and translation
Transcription
taking information of the DNA and turning it into RNA
What is copied during transcription?
copies a section of one strand
Translation
takes the information of mRNA and translates it into a different language (amino acids/proteins)
What is used during translation to translate the information of mRNA?
genetic code
What does the genetic code in translation convert the mRNA into?
amino acids
Genetic code
triplet code so that each nucleotide is read in groups of three that translates to a single amino acid
Genetic code is…
redundant, universal, triple code
Codon
group of three nucleotides
What macromolecule are nucleotides turned into?
proteins
Start codon
AUG
First amino acid in eukaryotes
Met
First amino acid in prokaryotes
fMet
Stop codons
UAG, UGA, UAA
mRNA
carries information to be translated to synthesize proteins
tRNA
takes individual amino acids and brings it into the ribosome to create proteins
RNA: secondary structure
clover leaf structure
Clover leaf structure
has amino acid site on one and and anticodon site on another
What is the clover leaf structure formed by?
hydrogen bonds
RNA: tertiary structure
backwards 7
Anticodon
complementary sequence of the codon
Backwards 7
have different anticodon on the bottom compared to the secondary structure
What does rRNA aid in?
ribosomal structure
Ribozyme
single enzyme molecule made of rRNA
Function of ribozymes
forms peptide bonds to bind and create proteins
Ribosome
enzyme complex that is large in size and is where protein synthesis occurs
How does tRNA and rRNA differ from mRNA?
tRNA and rRNA are similar to tools which can be used to aid in protein production while mRNA translates into synthesizing proteins
Molecules present in transcription
single DNA strand, RNA, RNA nucleotide, RNA polymerase
How many strands are required in transcription?
one stand: template strand
Template strand
strand which is used in transcription
Coding strand
contains the genetic code for the mRNA strand
Which strand is ignored in transcription?
coding strand
Transcription: RNA nucleotide use
there to create the RNA strand
Transcription: RNA polymerase use
enzyme used in transcription
Transcription: steps
initiation, elongation, termination
Transcription: initiation
RNA polymerase binds to the promoter region
Promoter region
where transcription starts; long sequence with many nucleotides that is not transcribed
Transcription: Elongation
nucleotides are added on to complement the template strand continuously until reaching termination
Transcription: Termination
RNA polymerase that hits a sequence which is 20 nucleotides long (termination sequence); this contains a DNA sequence
Transcription product
RNA/transcript
Nascent RNA
newly made RNA
Transcript
product
mRNA destined for transcription
has a sense strand
Sense strand
contains the information to create a protein
pre-RNA
nascent mRNA before it leaves the nucleus
What kind of cells are pre-RNA present in?
eukaryotic cells
What must RNA have before it leaves the nucleus in eukaryotic cells?
- 5’ cap added; molecule added to the beginning
- poly-A tail added at the 3’ end (many adenines added)
- remove introns: in-between important sequences (keep exons)
When does the RNA get to leave the nucleus to get translated?
mature mRNA
Molecules present in translation
mRNA, tRNA, ribosome
Charged tRNA
when the tRNA is carrying a amino acid
Uncharged tRNA
when the tRNA drops of amino acid and is not actively carrying an amino acid
What is the product of translation?
protein
Translation: steps
initiation, elongation, termination, protein folding, protein processing
When does protein folding occur?
during elongation
Translation: initiation
small ribosomal subunits bind to the the site, initiator tRNA binds, and then the large subunit binds
Translation: prokaryotic initiation
30S ribosomal subunit binds, initiator tRNA with fMET, 50S large subunit binds
Where does the 30S ribosomal subunit binds in prokaryotes?
shine-delgarno sequence
Translation: eukaryotic initiation
40S ribosomal subunit binds to the 5’ cap, initiaor tRNA with Met binds, 60S large subunit binds
Translation: tRNA binding site
A, P, E site
A site
amino site
P site
peptide site
E site
exit site: where tRNA leaves the ribosome
Translation: before the start of elongation what occupies the tRNA binding sites?
P is occupies, A+E are empty
Translation: elongation
next tRNA enters A site, ribozyme takes the peptide from the tRNA in the P site and cuts the covalent bond to form a peptide bond with the amino acid in the A site
Translation: translocation
mRNA is being pulled through the ribosomes 3 nucleotides down
Translation: termination
stop codon goes to the A site the ribosome stalls, the releasing factor will try and then attaches to the stop codon to break the bond between tRNA in the A site and the peptide chain is released
What happens to the molecules in translation after termination?
they are released and float around much like the peptide chain which is released
Protein folding
occurs during elongation and continues after being synthesized after termination
Protein processing
adding cofactors, adding function groups, cutting off different sections of the protein
mRNA modification in eukaryotic transcription/translation
5’ cap, poly AAA tail, introns spliced up
Prokaryote: location/timing of transcription/translation
- occurs in the cytoplasm
- transcription and translation are able to occur at the same time
Eukaryote: location/timing of transcription/translation
- transcription occurs in the nucleus, translation occurs in the cytoplasm/rough ER
- occurs at different times