T1 modules 3+4 Flashcards
basic functions of proteins
- transport + signalling (membrane pr-)
- movement + structure (muscles)
- enzymes
- defense
*structural differences cause functional differences
where is genetic information stored in eukaryotes vs prokaryotes? describe structure and function of these organelles.
NOTE: chloroplasts and mitochondria store their own genetic info
EUKARYOTES (larger genome)
nucleus
- double membrane (nuclear enveloppe), contains chromosomes
- NUCLEOLUS contains ribosomal RNA
- NUCLEAR PORES connect nucleus to cytosol to export ribosomes m+rRNA, import nucleic acid building blocks + enzymes needed for transcription
PROKARYOTES (genome smaller)
nucleoid
- stores supercoiled DNA
- PLASMIDS: circular subunits that contain 1 or 2 genes. Can be transferred
structure and function of ribosomes
enzymes used to translate mRNA to proteins
in eukaryotes:
- components made in nucleus, transported to cytoplasm via nucelar pores
- FREE RIBOSOMES (soluble in cytoplasm)
- BOUND RIBOSOMES (can attach to endoplasmic reticulum)
in prokaryotes
- made in cytosol
- only free ribosomes
describe basic protein structure
AMINO ACIDS
- amino group, central C and H, carboxyl group and R side group
MONOMERS: single AAs
RESIDUES: name for linked AAs
POLYMERS/POLYPEPTIDES: strand of monomers bonded via condensation rxns between carboxyl and amino groups (peptide bond)
describe structures and process of protein folding
structures
PRIMARY: polypeptide strand
- peptide (covalent) bonds between amino and carboxyl
SECONDARY: polypeptide folding
- alpha helix (HB between carbonyl and carboxyl)
- beta pleated sheets (HB between carboxyl and amino)
- order of polypeptide responsible for this shape
TERTIATRY: 3D pr- shape
- R groups responsible for folding
QUATERENARY: multiple pr- come together
- e.g. hemoglobin
process
- spontaneously
- assisted folding via
1) MOLECULAR CHAPERONES - bind to hydrophobic parts of pp chain to prevent incorrect folding
2) CHAPERONINS - isolation chambers to prevent iterference
describe the journey of a protein after synthesis
if made in cytosol will stay in cytosol
if made by bound ribosomes…
1) PR- TO ROUGH ENDOPLASMIC RETICULUM
signal recognition particle (SRP) guides pp chain into ER. modified, then some stay, some leave
- SRP binds to signal sequence on pp chain, stops translation
- SRP binds to SRP receptor on ER membrane
- SRP receptor brings ribosome to a transmembrane channel, pr- synth starts again, chain threaded through channel
some pr- stay in ER, to vesicles that branch from ER and fuse with the golgi apparatus
MODIFICATIONS IN ER AND GA: GLYCOSILATION (+ carb chains for stability, folding and recognition)
2) GOLGI APPARATUS
- can stay in GA or tagged and shipped out via transport vesicles to specific destinations
- vesicle bilayer fuses with destination bilayer, releases soluble pr- and embeds transmembrane pr-
- can also be transported along microtubules - a component of the cells cytoskeleton that acts like a highway for pr- transport
transmembrane pores
AQUAPORINS
moves water
structure
- embedded in cell membrane
- hydrophobic exterior
- hydropphilic core
function:
- doesn’t change shape to move water. water bonds with hydrophilic groups inside and then displaces other water to move through
BACTERIAL PORIN
transmembrane pr in prokaryotes
- beta sheets form tube
- found in chloroplast + mitochondria = evidence for endosymbiotic theory of organelle evolution
how did we find out DNA was the heredity storage molecule
NEUFELD:
bacterial injection into mice
R strain: benign
S strain: virulent
THE GRIFFITH’S EXPERIMENT
living benign cells can get genetic info from dead virulent cells via TRANSFORMATION
- heated S strain to kill bacteria
- made samples with DNA, RNA, pr- removed
- added to R strain
- only samples with DNA present were lethal -> DNA molecule causing transformation
define transformation
“A change in cell behaviour resulting from the incorporation of genetic material from outside of the cell.
describe DNA structure
NUCLEOTIDE
- phosphate group, 5-C sugar, nitrogenous base, hydroxyl group
NITROGENOUS BASES
purines: single rings
- cytosine
- thymine
pyrimidines: double rings
- adenine
- guanine
ASSEMBLING A DNA MOLECULE
- condensation reaction (phosphodiester bond) between phosphate on 5’ C and hydroxyl on 3’C creates SUGAR PHOSPHATE BACKBONE
OVERALL STRUCTURE
- base pairs G+C (3HB), A+T (2HB)
- sides run antiparallel
- major and minor grooves-
types of RNA and their functions
mRNA: single stranded, translated to pr-
tRNA: never translated, carries AA to ribosomes during translation
rRNA: transcribed from ribosomal genes, perform translation
differences between DNA and RNA
STRUCTURE
DNA
- only 1 OH group on ribose sugar
- thymine
- T+A C+G
RNA
- 2 OH groups on ribose sugar
- uracil
- U+A C+G
how to tell if amino acids are hydrophilic or hydrophobic
philic
- able to make HB (will see NH2, OH)
phobic
- will see lots of carbons (like fatty acid chain, will be hydrophobic)
- benzene rings
name special amino acids
glycine, cystene and proline
