lecture 5&6 Flashcards
what is the purpose of nucleic acids
store and transmit genes
program amino acid sequence of polypeptide (proteins)
structure of nucleic acids
made of nucleotides
what are the two types of nucleic acids
deoxyribonucleic acid (dna)
ribonucleic acid (rna)
what does the dna do
stores information for protein synthesis
acts as a blueprint to make the proteins
what does the rna do
directs protein synthesis
acts as messenger to relay information from dna
what replaces thymine in rna
uracil
what is the structure of nucleic acids
a phosphate molecule
a 5 carbon sugar
a nitrogenous base
what sugars do dna and rna have
dna has deoxyribose
rna has ribose
what kind of formation do the dna strands have
antiparallel formation
3 prime to 5 prime
what are the functions of histones
wind the dna to fit 2m into 10 nanometers of space
control gene activation and deactivation
what do gene have to do with proteins
genes have the information needed to make the specific protein and the primary sequence of the protein
what are the two major steps in protein synthesis
transcription
translation
what are the steps of transcription
- separation of dna at a particular gene
- synthesis of mRNA (using uracil)
- mRNA is sent to cytosol
what is the start codon of transcription
AUG
do the start/stop codon code for amino acids
only the start codon
what are codons
group of three nucleotides that code for one amino acid
what are the characteristics of mRNA
single stranded
synthesized in nucleus with the help of enzymes and dna
has the information of one gene
what is translation
the assembly of the protein’s primary structure according to the codon sequence on the mRNA
what does the tRNA do
decode the codons of mRNA
how does the tRNA work
it has anti codons that complementary bind to the mRNA codons while creating an amino acid chain
how many codons are there
64 (1 start, 3 stop and 61 amino acids)
how many anticodons are there
31 (many codons code for the same amino acid)
what does the rRNA do
links mRNA and tRNA
what is the structure of rRNA
3 tRNA binding sites:
1. A site (aminoacyl-tRNA)
2. P site (peptidyl-tRNA)
3. E site (exit site)
what is the process of translation
tRNA attaches to the start codon at the P site
the next tRNA attaches to the A site
the ribosome moves along the mRNA which makes the tRNA leave through the exit site
this builds the amino acid chain until the stop codon is reached
when the stop codon is reached what happens
a release factor binds to the A site which causes a water molecule to be added to hydrolysis the chain
this releases the polypeptide
what is the range of cell size*
8 to 100 um
why are cells so small*
because as cell size increase the metabolic needs of the cell increases
the surface area is smaller than the volume so it can’t meet the demands
what does having a smaller volume mean for a cell*
less metabolic demands but also less surface area to transport materials in and out
what is the range of size for prokaryotic cells*
1-10 um
how do you classify organisms in the bacteria domain*
using the gram test
what are characteristics of gram positive bacteria*
stain blue/purple
have a thick peptidoglycan layer after the plasma membrane
what are the characteristics of a gram negative bacteria*
stain red
have a thin peptidoglycan layer
have an extra outer membrane
what are the functions of cell walls*
rigidity
protection from bursting
do antibiotics have a harder time going through gram + or - bacteria*
gram - (extra outer membrane)
what are the functions of capsule on prokaryotes*
prevents the cell drying
helps cell stick to things
protects cell from white blood cells (no antigens so w.b.c. can’t recognize it as enemy)
what are three characteristics of the domain archaea*
have histones (proteins) associated with dna like eukaryotic cells
have s layer on cell surface
have a cell wall (no peptidoglycan)
what is the s layer on archaea composed of*
glycosylated proteins (have glucose)
what are the two major categories of organelles*
membranous organelles
non membranous organelles
examples of membranous organelles*
plasma membrane, cytoplasm, nucleus
smooth and rough ER, golgi, vesicles, lysosomes, peroxisome, mitochondria, chloroplast, vacuoles
examples of non membranous components*
nucleolus, ribosomes, cytoskeleton, centrosome, cilia, flagella, cell junctions, cell wall, extracellular matrix
why do we need the plasma membrane*
to regulate movement in and out of the cell
the maintain the interior environment balanced (critical for cell processes and function)
what are the functions of the plasma membrane*
cell adhesion, recognition, communication and regulating interior env.
what is the plasma membrane made of*
phospholipid molecules
protein molecules
cholesterol
what do phospholipids do in the plasma membrane*
selectively permeable
allows some substances to cross it better than others
what is the fluid mosaic model*
proteins moving sideways through the plasma membrane’s bilayer
what is the difference between the cytoplasm and the cytosol*
cytoplasm is the region between the nucleus and the plasma membrane
cytosol is the fluid substance inside the cell which contains the organelles
is the nucleolus membrane bound*
no (its inside the nucleus and makes the ribosomes)
what does the membrane of the nucleus look like*
looks like a double membrane but is actually folded over itself (nuclear envelope)
has pores to allow exchange of materials
what is a chromatin*
loosely arranged dna and protein
what is a chromosome*
tightly packed dna and histones (proteins) in x shape (46 chromosomes total)
what are the two types of endoplasmic reticulum and what makes them different*
rough ER (has ribosomes/dots)
smooth ER
what is the ER membrane made of*
continuation of nuclear envelope
weaves in sheets
what are cisternae*
tubules and sacs (lipid bilayer) of the ER membrane
what are the functions of the rough ER*
produce proteins (ribosomes)
distribute proteins to other cells or organelles
modify proteins
where does the rough ER send most of its proteins*
golgi apparatus
how does the rough ER modify proteins*
fold into 3D shape
enzyme can modify proteins by adding carbs or lipids to them
what are the functions of the smooth ER*
synthesize and transport proteins
enzymes detoxify poisons and drugs (liver)
metabolizes carbs
storage of calcium
what are the functions of the golgi apparatus*
packaging and shipping centre of molecules
chemical modification of molecules
synthesizes carbs
characteristics of golgi apparatus*
structurally similar to ER
5-20 membranous sacs (cisternae)
what is a vesicle*
a hollow sphere with a membrane identical to the plasma membrane
what is the function of vesicles*
store/transport chemicals around the cell
what are the two types of vesicles, who makes them and where do they go*
transport (ER makes it to get proteins to golgi)
secretory (golgi makes it to go to the plasma membrane or around the cell)
what is the function of a lysosome and who makes them*
destroy pathogens and damaged organelles
golgi makes them
how does a lysosome work*
its a vesicle that contains digestive enzymes (pH 5 so acidic) which are only active inside its membrane to prevent damaging the cell in case of leakage (cells pH is 7.2)
what are the processes lysosomes go through called*
phagocytosis
autophagy
what is phagocytosis*
lysosome digesting materials from outside the cell
what is autophagy*
lysosome digesting organelles from inside the cell (itself)
how do lysosome digest things*
engulfs them
what are the functions of peroxisomes*
fatty acid metabolism
detoxify harmful compounds (liver)
gets rid of the hydrogen peroxide released when enzymes transfer hydrogen to oxygen (ex. phagocytosis and autophagy)
what allows peroxisome to detoxify hydrogen peroxide*
has enzyme that turns H2O2 to water
what are the functions of mitochondria*
power house of the cell
aerobic respiration
makes ATP from glucose
how many membranes do mitochondrias have and what are they made of*
2 membranes that each have a phospholipid bilayer
what is the endosymbiont theory*
theory that millions of years ago a cell engulfed another and developed a symbiotic relationship instead of digesting it (believed to have happened with mitochondria and chloroplast because they have the basic structure of a cell)
