Cell Bio Flashcards
Membrane function
holds internal content of the cell separate from the outside and regulate what gets into and out of the cell.
Water, gases (O2, CO2), small noncharged or non-polar molecules pass through NA+, large molecules like sugar cannot
phospholipid bilayer
- two layers of phospholipids, flexible structure describes a fluid mosaic model
- cholesterol is an integral part of the cell membrane, is in the hydrophobic portion keeps the membrane flexible
Membrane proteins
associated with the membrane - some are external, some are on the inside, and some are transmembrane proteins (across)
function
1) acting as receptors
2) channels or pumps for ions and other material to cross the membrane
3) signaling across the membrane
Passive movements
diffusion
osmosis
diffusion
the tendency of molecules to spread from areas of high concentration to areas of low concentration in order to reach equal concentration throughout- the process is driven by the concentration gradient
Osmosis
movement of water across a cell membrane from high concentration to low areas
thing of salt
isotonic
equal salt concentration inside and outside of cells
hypotonic
salt concentrations outside the cell are less than those inside the cell,
water moves into the cell to reduce the internal salt concentration
the cell will swell and may eventually burst
Hypertonic
salt concentrations outside the cell are greater than those inside the cell.
water moves out of the cell to increase the internal salt concentration, the cell will shrink
active movement
requires cellular energy
Active transport
involves transmembrane protein acting as “pumps”- ATP is required - into the cell or “pumping out” materials such as ions to maintain unequal concentration such as K+ or Na+
Endocytosis
bringing something into the cell across the membrane
- Receptor-mediated endocytosis
- phagocytosis
- pinocytosis
receptor-mediated endocytosis
the molecule binds to a receptor on the surface of the cell- that triggers the receptors and the material bound to it to be brought in through the cell membrane to the inside of the cell in a vesicle
Phagocytosis
cell engulfs solid material (white blood cells ingesting a bacteria)- bring it in through the cell membrane and breaks it down
Pinocytosis
cell engulfs and brings in liquid material
exocytosis
moving something in vesicle from the inside of the cell to be released to the outside
Cytoplasm
the fluid or gel inside the cell (cytosol) and the various organelles
Ribosomes
structure and function
very small made up of 2 circular subunits-found free in the cytoplasm or attached to the round endoplasmic reticulum
the function is to make protein
Endoplasmic reticulum
structure and function
a ‘stack’ of folded interconnected membranes-start at the edge of the nuclear membrane
function- two type
rough: covered with ribosomes=make protein
smoot: make lipids
Golgi Apparatus
structure and function
a series of stacked and folded membranes (similar to but smaller than the Er)
function
1) adding sugars to the molecules
2) packaging material for movement to another part of the cell or release from the cell- the material is placed in a vesical and moved elsewhere within the cell or released by exocytosis
Lysosomes
structure and function
small, rounded, membrane-bounded structure
function- contains digestive enzymes and other molecules- breaks things ingested by the cell
Vacuoles
a membrane-bounded “bubble” within a cell that stores something (ex. food vacuole)
Mitochondria
structure and function
kidney-shaped- contain highly infolded internal membranes called cristae- this creates additional surface areas and are sites for cellular respiration to take place and the ATP synthase to function. They have their own DNA which is passed from mother to offspring
function- production of ATP, cellular energy
Chloroplasts
specialized structure for carrying out photosynthesis- contains chlorophyll and membrane systems including the thylakoid membrane
Cytoskeleton
group 3 different protein strands with a different function:
1) intermediate filaments- internal “skeleton” providing structure for the cell
2) microtubules or tubulin- the intracellular movement of materials from places to places within the cell, are found in the cilia and flagella, and form the mitotic spindle involved in mitosis and meiosis
3) microfilaments- thin filaments of actin (and myosin) for movements of the cell itself such has amoeboid motion.
microtubules are also found in cilia and flagella
Nucleus
nuclear membrane
the membrane that surrounds the chromosomes-in it is nuclear pores-small holes which allow the material to pass from the nucleus to the cytoplasm
Nucleus
chromosome
a strand of DNA and protein (chromatin)- the DNA exists in a highly coiled state-supercoiled- the proteins (histones) pack the DNA into a small space and are also involved in controlling gene expression
Mitosis
general concept
occurs in the body (somatic cells) mitosis is replication fo the nucleus.
Prophase
cell prepares to divide: the nuclear membrane breaks down and the spindle apparatus forms
Metaphase
two sets of chromosomes line up in the middle of the cell
anaphase
two sets of chromos move apart to the opposite ends
telophase
nucleus reforms and the spindle apparatus break down
interphase
the period between cells mitoses
The cell cycle
refers to the various phases a cell goes through-Mitosis (M) is one of them-a cell spends most of its time in the growth (G), or DNA duplication (S) phase of the cell cycle
Meiosis
general concepts-
- occurs in reproductive organ cells (germ cells) sperm and egg
- normal body cells (somatic cells) have 2 chromosomes in pairs-condiction referred to as diploid and indicated by 2n
- Meiosis results in the formation of germ cells which have single chromosomes- a condition referred to as haploid and indicated by 1n (23)
cytokinesis
replication of the rest of the cell (remember mitosis is only the nucleus)- cytoplasm and organelles
Cell Metabolism
general concepts
metabolism is all the various biochemical reactions taking place
anabolism- build things up from smaller components or subunits
catabolism - breaking molecules down
Enzymes
general concepts
carry out all the metabolic reactions in the cells, each enzyme specific for a reaction and repeating the reaction
- catalyst lower the energy needed for the reaction to happen
- substrate-substance that enzyme acts upon, depends on the substrate shape and enzyme’s active site
Coenzymes and Cofactors
extra pieces needed by some enzyme to function, two types
- Coenzymes: organic (thiamine, riboflavin, niacin) mainly vitamins (fat-soluble and water soluble)
- Cofactors: inorganic (iron, zinc, magnesium, copper) a mineral
Fat-soluble vitamins
A, E, D, and K; taking fat-soluble vitamins in high amounts can lead to toxicity to the liver, as they are not excreted well
water-soluble vitamins
C, also known as ascorbic acid, various B vitamins (B1, (thiamine) B2 (riboflavin), B3 (niacin), B6, B7, B12)
the disease resulting from a deficiency in vitamin C is known as scurvy
Control activity of the enzyme
amount of product produced act as a single that will bind to and shut down the enzyme, this is known as the feedback inhibiting
Aerobic Respiration
list steps
With oxygen
- glycolysis- glucose is broken down into 2 pyruvic acids, 2 ATP is made
- Kreb’s Cycle- citric acid cycle- the 2 pyruvic is broken down (from Glycolysis) into CO2, 2ATP, and NADH and FADH2 are also produced
- Oxidative phosphorylation- electron transport chain, oxidative-reduction happens here, most ATP made, kind oxygen (H+), water is waste product
Anaerobic Respiration
Fermentation
No O2,
- terminal acceptor- instead of oxygen in the electron transport chain, it is sulfur, H2S is produced instead of water
- Fermentation- involves glycolysis (and few steps) and does not go onto Kreb’s cycle and Electron transport chain. the least efficient process than aerobic, and 2 ATP result, and alcohol and acetic acid are formed
Photosynthesis
general concept
CO2 and H2O are input and O2 is the waste product
- Light reaction- light is required, the goal is to generate ATP
Photosynthetic Pigments
the Key molecule is this process chlorophyll, accessory pigments are also involved- they trap the energy form different wavelengths of sunlight
Photosynthesis, ATP production
water is split- (O and H+) - the protons are passed through an electron transport chain to generate ATP while Oxygen is left as a waste product
Dark reaction (Calvin-Benson cycle)
light is not required for this-The ATP generated in the light reaction is now used (along with CO2) to make sugar and other molecules
Chemosynthesis
an unusual form of anabolism only carried out by certain bacteria “photosynthesis without the sun”, involves the energy of certain chemical reaction (NO2-NO3)
example: communities found miles under the surface around undersea volcanoes, bacteria get the energy from the minerals coming out of the volcanoes
