U2 - Genetics Flashcards
what is a nucleic acid
large biomolecules essential in all cells and viruses
purine
double carbon ring structure with adenine and guanine
pyrimidine
single carbon ring structure with thymine and cytosine and uracil (RNA)
DNA vs RNA
DNA
→ double stranded
→ deoxyribose as sugar base
→ stays in nucleus
→ inheritance of genetic material
→ thymine
RNA
→ single stranded
→ ribose as sugar base
→ can leave nucleus
→ protein synethsis
→ uracil
difference in hydrogen bonds holding the nucleic acids tgt
A has double hydrogen bonds to T
G has triple hydrogen bonds to C
what is nucleotide (monomer)
A molecule that is the basic building block of the nucleic acids DNA and RNA
what is phosphodiester bond
this bond links 5’ phosphate group of one nucleotide with the 3’ hydroxyl group of another nucleotide
what is glycosyl bond
bond between sugar and nitrogenous base in nucleic acid (DNA and RNA)
ATP process
ADP process
a-p-p-p (ATP) releases energy meaning it is CATABOLIC
app (ADP) puts in energy meaning it is ANABOLIC
distance between each nucleotide in DNA and distance between each full turn
between nucleotide: 0.34nm
1 complete turn: 3.4nm
erwin chargaff
→ 1950
→ Chargaff’s rule; discovered A pairs with T and G pairs with C
rosalind franklin
→ 1953
→ used x-ray difffraction to discover helical nature of DNA
watson and crick
→ 1953
→ made the model of DNA
histone
a pos. charged protein that DNA is bound to in a chromosome
nucleosome
a complex of 8 histones enveloped by DNA
telomere
a long sequence of repetitive, non-coding DNA found at end of chromosomes
centromere
constricted region of chromosome that holds two replicated chromosome strands together
AT and CG diference
AT is held by double bonds
CG is held by triple bonds
components of DNA (draw)
chromosome, centromere, chromatid, supercoiled 30nm fibre, chromatin fibre, nucleosome, nucleosomes, histones, DNA double helix (20nm)
what did fred griffith discover and when
1928 - transformation, R-forms look rough (no capsule) and S-form looks smooth (Has capsule), heat killed cells and he studied bacteria causing pneumonia
what did beadle and tatum discover and when
draw out diagram to undertand
1941- investigated the ‘one-gene-one-enzyme’ hypothesis using bread mould.
A———->B———->C———>D——–>E
E1. - E2. - E3.
gene 1 - gene 2 - gene 3
his theory found that x-rays destroy gene 2 therefore no enzymes and mould dies unless supplmented with C,D, or E
lac vs trp operon?
lac operon is inducible and encodes enzymes that break down lactose for food
trp operon is repressible that encodes enzymes that make tryptophan (AA)
promoter region vs operator region
promoter region is DNA sequence where RNA polymerase binds to initiate transcription
Operator is the DNA segment where the repressor molecule binds to operon
Explain how gene regulation is different in eukaryotic cells and prokaryotic cells.
prokaryotes don’t have nucleuses so the process is much simpler, transcription and translation can occur at the same time at opposite ends of mRNA.
in eukaryotic cells, its regulated by repressors as well as by transcriptional activators. eukaryotes have to transcribe and then have a process for mRNA processing
define operon, operator, repressor
operon - link of genes that regulates other genes that are responsible for protein synthesis
operator - segment of DNA where
repressor binds to, preventing transcription of certain genes
repressor - protein that binds to the operator sequence to inhibit gene transcription
why is it advantageous to the cell to have some of its genes under regulation
To control when proteins are synthesized and when they are broken down.
- Allows cells to conserve energy and space.
- Convenient and more efficient to synthesize proteins only when needed..
how to determine between inducers or corepressors
inducers - increase transcription
corepressors - decrease transcription
p-site vs a-site
p site - (peptidyl) the second binding site for tRNA in the ribosome.
a site - (aminoacyl) the first binding site in the ribosome
codon vs anti codon
codon - three-nucleotide sequence found on mRNA that codes for a certain amino acid during translation
anticodon - three-nucleotide sequence found on tRNA that binds to the corresponding mRNA sequence.
start codon vs stop codon
start codon initiates the translation
stop codon ends the translation
Three types of RNA must be functioning properly to ensure normal protein synthesis. Identify the three types of RNA that are needed and explain the critical role that each one plays during translation.
mRNA - carries information from DNA in nucleus to ribosomes
tRNA - carries AA to ribosomes during translation (builds AA chain)
rRNA - forms ribosomes (essential in protein synthesis)
The following sequence was isolated from a fragment of mRNA:
5’ – GGC CCA UAG AUG CCA CCG GGA AAA GAC UGA GCC CCG – 3’
Translate the sequence into protein starting with the start codon.
5’ – GGC CCA UAG AUG CCA CCG GGA AAA GAC UGA GCC CCG – 3’
AUG is the start codon (met)
translated AUG (start) CCA CCG GGA AAA GAC UGA (stop) : Met-Pro-Pro-Gly-Lys-Asp
Differentiate between introns and exons
introns - non coding sections of RNA transcript
exons - sections of DNA that code for proteins
differences in prokaryote and eukaroyote transcription
prokaryotes
- coupled with translation
- lacks introns meaning no excision (removing/cutting out)
eukaryotes
- occurs in nucleus
- spliceosomes (large RNA protein) cut introns out and exons join together
