2.4: Proteins Flashcards
how many amino acids are there in polypeptides synthesized on ribosomes
20 different amino acids
what bond links amino acids?
peptide bond
formation of a dipeptide
from amino acids
amino acid + amino acid –––––––>
dipeptide + water
characteristics of R group in amino acids
- can be polar (hydrophillic)
- can be non-polar (hydrophobic)
- can be negatively or postively charged
- can contain sulfur
what do characteristics of the R group do?
impacts the properties and behaviour of the protein
what do ribosomes do
they are the molecule within cells that facilitate the formation of peptide bonds and thus they are whwere polypeptides are synthesized
most organisms assemble polypeptides from the _________ amino acids
same
why are there infinite possibilities of polypeptides?
- can be any length
- 20 amino acids
- amino acids in any order or combination
- basically limitless
ribosomes aree the site of polypeptide synthesis, but ribosomes need a template– the ________________ which in turn, is ______________ by __________________ molecules, which, in turn, carry __________________.
messenger RNA
translated
transfer RNA
specific amino acids`
Genes are….
codes for making polypeptides
mRNA (messenger RNA) is…
a message from nucleus to ribosome
- gives intructions on how to put polypeptide together
genetic code is…
the sequence of bases on mRNA
- tells ribosome which amino acids to use
open reading frame
the base sequence that codes for polypeptide
- only occupy small portion of total DNA in species
lysozome
- has one polypeptide
- enzymes in secreted biody fluids kills bacterial by breaking down the peptidoglycan in their cell walls
collagen
- has three polypeptides
- strong, elestic structural protein found in connective tissues
hemogoblin
- has four polypeptides
- transport protein in red blood cells
- binds oxygen from long and releases into tissues with lower oxygen concentration
polypeptides are the _______________ of protein structure
base or primary level
how different amino acids interact with each other and their surrounding determines…
their 3d shape
before polypeptides are functional they must…
fold into specific structures based on the order/ structure of their amino acid sequence
primary protein structure
sequence of a chain of amino acids
secondary protein structure
hydrogen bonding of the peptide backbone causes the amino acids to fold into a repeating pattern
tertiary protein structure
three dimensional folding pattern of a protein due to side chain interactions
quaternary protein structure
protein consiting of more than once amino acid chain
shape: fibrous proteins vs globular proteins
fibrous proteins:
- long and narrow
globular protein:
- rounded/spherical
role: fibrous proteins vs globular proteins
fibrous:
- structural
- strength and support
globular protein
- functional
- catalytic, transport etc
solubility: fibrous protein vs globular protein
fibrous:
- generally insuluble in water
globular:
- generally soluble in water
sequence: fibrous protein vs globular protein
fibrous:
- repetitive amino acid sequence
globular:
- irregular amino acid sequence
stability: fibrous protein vs globular protein
fibrous:
- less sensitive to chnages in heat, pH etc
globular:
- more sensitive to heat, pH etc
examples: fibrous protein vs globular protein
fibrous:
- collagen, myosin, fibrin, actin, keratin, elastin
globularL
- catalase, haemoglobin, insulin, immunoglobin
The 3D conformation of protein is stabilized _____________________ between R groups of amino acids within the molecule
by bonds or interactions
Most of these bonds are relatively weak, and can be _______________ with exposure to heat or changes in pH
disrupted or broken
breaking or disrupting bonds results in a change to the ______________ of the protein, which is called __________ (usually permanent), this also causes a loss in ___________
conformation
denaturation
function
renaturation
when protein regains its original 3D shape (and function)
- can happen if the exposure is minimal, and the factor removed after a short time
temperature on denaturation
- causes vibrations within the molecule that can break intermolecular bonds or interactions
- Different proteins have different tolerances to heat
pH on dentauration (too acidic or too basic)
- Changes the charges on R groups, breaking ionic bonds within the protein or causing new ionic bonds to form
- Different proteins have different optimal pH values
rubisco
- abbrev. for ribulose bisphosphate carboxylase
- very important enzyme
- catalyses reaction that fixes carbon fixes co2 from atmsophere
- provides source of carbon that can produce carbon compounds
- found in high concentration in leaves
insulin
- hormone that gives signal to cells in body to absorb/reduce/regulate glucose conc. in blood
- cells have receptor to let insulin to bind to
- insulin is secreted in beta cells in pancreas
immunogoblin
- aka antibodies
- binds to antigens on bacteria/pathogens
- casues response for phagocytes to engulf pathogens
- basis for immunity to disease
rhodopsin
- a pigement that absorbs light for vision
- contains light sensitive molecule surrounded by opsin polypeptide
- when it absorbs a single photon of light, it chnages shape, causing opsin to also change shape, leading to impulse being sent to brain
spider silk
- conatains regions where polypeptides form parallel arrays
- very exrensble and resistent to breaking
proteome
all porteins made by a cell, tissue or organism
genome
all the genes of a cell, tissue or organism
proteome vs genome
proteomes are unique among individuals of same species, genome is not
