BIO TEST 1 MODULES 1 & 2 Flashcards
What is a zygote?
a fertilized egg
What are the characterstics of eukaryotic cells?
Compartmentalized organelles;
nucleus;
Plants cells, animals cells fungi
What are the characteristics of prokaryotic cells?
No compartmentalized organelles;
No nucleus but has a nuclear space and a long ribosome
What is a microbiome?
all the population of microorganisms or microbes in an organism
How many microorganisms does a healthy human have?
10,000
STREPTOCOCCUS SALIVARIUS
an inhabitant of the upper respiratory tract and oral cavity and it contributes to dental plaque;
One of the 1st microbes to colonize a germ-free newborn’s dental cavity and gastrointestinal tract
STAPHYLOCOCCUS HAEMOLYTICUS
Resides on the skin;
Its harmless for the most part but can be pathogenic in the body;
Can cause the immune system to become active
BACTEROIDES THETAIOTAOMICRON
A very common intestinal bacteria
Forms enzymes which can break down plant material we ingest (oat fiber)
What are the 4 macromolecules that make up living cells?
Nucleic acids, proteins, phospholipids, carbohydrates
What is a nucleic acid?
has hereditary information and is found in DNA; chromosome/nucleoid
What are proteins?
the structural components of the cell, and can perform metabolic activities (ribosomes, enzymes)
Carbohydrates (polysaccharides)
Important structural components of many cells and sources of stored energy
Phospholipids
primary component of the cell membrane
Why is cell permeability important?
Important to separate internal and external environments of the cell;
Allows controlled entry of important compounds and disposal of metabolic wastes
What are cell membranes made up of?
Made up of lipid macromolecules which have hydrophobic and hydrophilic properties. This is known as the phospholipid bilayer
are the hydrocarbon fatty acid tails polar or non-polar?
non-polar (hydrophobic)
is the phosphate head group polar or non-polar?
polar (hydrophilic)
What are lipid micelles?
formed by phosphates; important for absorbing fat-soluble vitamins and complex lipids in the body; generate spontaneously without energy; water will interact with head regions and lipid aggregates form spontaneously, without energy
What are phospholipids made up of?
Has a glycerol molecule linked to 2 fatty acid tails;
Hydrophobic region is where fatty acids are located;
Hydrophilic head groups (glycerol plus phosphate)
what is a distinct characteristic of phospholipids?
amphipathic
hydrocarbon chains in phospholipids
made of hydrocarbon chains which are usually made up of 16-18 carbons in a single chain;
bonds can be single (saturated) or in double bonds (unsaturated);
Single chains are straight, left tail
Chains with double bind will have kink at the end (right tail)
how does the saturation of fatty acids affect the fluidity of cell membranes?
longer chains are packed together more tightly than the shorter ones, reduces permeability; areas that are more fluid will have unsaturated tails (non-lipid raft region); saturated areas less fluid because there will be stronger hydrophobic regions (lipid raft)
What are the factors that affect fluidity of a cell membrane?
unsaturated and saturated fatty acids, number of carbons in the fatty acid tails, temperature, presence/absence of steroids in the form of cholesterol
how does number of carbons in the fatty acid tails affect fluidity of cell membranes?
double bonds create kinks in the phospholipid, pushes neighbouring phospholipids far apart making it more fluid
how does temperature affect the fluidity of cell membranes?
high temps = more fluidity (cold adapted organisms have unsaturated phospholipids in their membranes to promote fluidity_
how does the presence/absence of cholestrol affect membrane fluidity?
cholesterol works like lipids and keeps phospholipids fluid in nature;
Makes sure that it isn’t solid at low temps
what is a lipid draft?
region of low fluidity
what does a lipid raft do?
holds macromolecules together in a membrane; gather proteins which are used in metabolic pathways; collection of receptors on cell surface
fluidity in lipid rafts
taller due to longer phospholipid hydrocarbon tails (straight tails not kinked); allows phospholipids to pack closer together; decreases fluidity to hold macromolecules on raft; higher cholestrol concentration decreases fluidity in lipid raft
later mobility of cell membrane (fluorescent tagging lecture example)
ER membrane is fluid (synthesizes proteins); nuclear membraneis not as fluid (because nuclear pores are kept in particular places which allow controlled movement of DNA and RNA)
how does low permeability affect cholesterol?
Will have fewer unsaturated fatty acids and more cholesterol
High cholesterol reduces the amount of water and water-soluble molecules that move through membranes
how does high permeability affect cholesterol?
Will have more unsaturated fatty acids and less cholesterol
how is the cell membrane selectively permeable?
Small ions can move across the membrane along a concentration gradient (areas of high to low concentration) through diffusion;
Small, non-polar, hydrophobic molecules pass easily;
Charged, polar molecules have a hard time, and sometimes do not pass at all
what are cell membranes made up of?
lipids, proteins, and carbohydrates; mostly carbs
Why are lipid bilayers useful in proteins?
help transport substances across the membrane
what does the fluid mosaic model do?
predicts the movement of the cell membrane and its fluidity
where can membrane associated proteins be found?
on the interior exterior of the cell or embedded in the phospholipid bilayer
what are protein channels made up of?
amphipathic proteins
what does the protein channel do?
facilitates the movement of hydrophilic molecules across the membrane
passive/simple diffusion
From areas of high to low concentration (along a concentration gradient;
Movement of small molecules in the direction of the concentration gradient;
Crosses the phospholipid bilayer itself
facilitated diffusion/passive transport
From areas of high to low concentration (along a gradient)
active transport
Molecules are moving against the concentration gradient (fueled by energy from the hydrolysis of ATP);
Protein pumps needed
how does simple diffusion allow materials to cross the cell membrane?
Movement of lipid-soluble molecules, gasses and uncharged polar molecules and some water across the membrane without the need of energy;
Moves in and out of the cell through the membrane;
From area of high concentration (exterior of cell) to low concentration (interior of cell)
how does facilitated diffusion allow materials to cross the cell membrane?
Movement of small molecules along the concentration gradient;
Integral proteins are used to provide a hydrophilic core which allows hydrophilic molecules to pass through;
Movement along a concentration gradient
No energy is required
osmosis
This is the movement of water from areas of high solute concentration to areas of low solute concentration through a selectively permeable membrane until equilibrium is reached;
Water uses osmosis to move through cell membranes
aquaporin transmembrane proteins
allow water to pass through hydrophilic protein core; allows osmosis to occur 10x faster than it takes for water to move across a phospholipid bilayer
tonicity
amount of solutes in in environment/solution
isotonic
Environment has same concentration as cell;
No net movement of water
hypotonic
Environment has less concentration than the cell;
Net movement of water into the cell which causes cell to swell up
hypertonic
Environment has more concentration than the cell;
Net movement of water out of the cell which causes the cell to shrivel
primary active transport
To pump molecules against the concentration gradient
Uses chemical energy in the form of ATP to transport all species of solutes across a membrane against a concentration gradient
secondary active transport
When neighboring proteins use advantage of electrochemical gradients established by the primary active transport pumps to move solutes across a membrane
why are sodium potassium pumps important?
allow the cell to establish a difference in concentration of sodium and potassium on either side of a cell membrane;
There is usually a surplus of sodium outside the cell and a surplus of potassium inside the cell relative to the extracellular environment
what is the sodium potassium pump?
repeated cycle, 3 NA out and 2 K into axon; hydrolysis of ATP provides the phosphate group needed for the transport protein, and will cause a conformational change in the shape of the transport protein, which releases the sodium ions into the extracellular fluid;
The potassium will bind to the protein and will enter the cell and the phosphate group is released and the protein returns to its original shape
proterozoic eon
appearance of 1st photosynthetic cells
prokaryotes vs eukaryotes
prokaryotic cells lack distinct compartmentalized nucleus; eukaryotes have double membraned nucleus that separated genetic material from rest of inside of the cell
similarity bw eukaryotic and prokaryotic cells
external plasma membrane that separates inside of the cell from the outside
function of mitochondria
Produce energy from the food we eat through cellular respiration
Plant and animal cells will release the chemical energy stored in the bonds of carbohydrate molecules and will capture it in the form of ATP
Chemical energy in the form of ATP is generated through the mitochondria through the breakdown of sugars
structure of the mitochondria
Each mitochondria has 2 membranes: outer membrane (surrounding organelle) and inner membrane connected to the cristea
The cristea is where most ATP is synthesized in eukaryotic cells
chloroplasts
Found in plants and they convert light energy into chemical energy
Chemical energy stored in the bonds of carbohydrate molecules
Has a double membrane and is filled with stacks of thylakoids known as grana
These membranes contain the enzymes and pigments needed for photosynthesis
Evolved from photosynthetic cyanobacteria
endosymbiotic relationships
Organisms which form a symbiotic relationship with another cell or organism
how do eukaryotic cells benefit from bacterial processes?
Anaerobic ancestral eukaryotes had the ability to form small amounts of ATP from carbon compounds and by interactions with aerobic bacteria
Eventually the anaerobic eukaryotes may have engulfed these aerobic bacteria, which now supplies it with large amounts of energy. The engulfed cell benefits because it has a safe environment and a supply of carbon compounds
how does phagocytosis help prokaryotes
allows prokaryotes to compartmentalize genetic material into a nucleus to allow for greater control over regulation of genes and processing proteins
Eventually these nuclei containing cells became hosts for aerobic prokaryotes and photosynthesis prokaryotes
endosymbiotic relationships (green algae)
Has living bacteria inside protists (grouping of mostly unicellular eukaryotic organisms)
The photosynthetic products are shared with the protist host, so both organisms benefit
endosymbiotic relationships (corals)
Corals live symbiotically with microbes known as dinoflagellates;
Dinoflagellates will photosynthesize and release all their products to coral
endosymbiotic relationships (sea slug and algae)
A sea slug consumes photosynthetic algae and harvests the chloroplasts from the algal cells
The chloroplasts remain in the sea slug
why are organelles and compartmentalization important?
Compartmentalized organelles carry out distinct functions as they store unique sets of enzymes which carry out specific biochemical functions;
By keeping these organelles close together various processes are done efficiently – photosynthesis and cellular respiration;
A high concentration of enzymes in an organelle allow for efficient chemical reactions
