Cell Biology Flashcards
cell membrane
holds in the internal contents of the cell and regulates what gets into and out of the cell
phospholipid bilayer
2 layers of phospholipids
flexible
fluid mosaic model
cholesterol
integral part of the cell membrane
keeps it flexible
membrane proteins
associated with the membrane
some on the outside, some on the inside, and some are transmembrane proteins
functions: act as receptors, act as channels for ions and other materials to cross the membrane, signal across the membrane
diffusion
passive transport
molecules spread from areas of high concentration to areas of low concentration to reach equilibrium
osmosis
passive transport
movement of water across cell membrane
isotonic
equal salt concentration inside and outside the cell
hypotonic
salt concentrations outside the cell are less than those inside the cell
water moves inside the cell
cell will swell and may burst
hypertonic
salt concentrations outside the cell are greater than those inside the cell
water will move outside the cell
cell will shrink
active transport
requires energy-ATP
transmembrane proteins act as pumps
brings materials into the cell or pump out materials such as ions to maintain unequal concentrations (e.g. K+ and NA+ inside and outside neurons)
endocytosis
bringing something into the cell across the membrane
receptor-mediated endocytosis
allows the cell to bring in specific materials that it needs
molecule binds to a receptor on the surface of the cell that triggers the receptor and the material bound to it will be brought in through the cell membrane to the inside of the cell
phagocytosis
cell engulfs solid material and brings it in through the cell membrane and breaks it down
pinocytosis
cell engulf liquid material
exocytosis
something from the inside of the cell is released to the outside
cytoplasm
fluid or gel inside the cell
ribosomes
very small
made of 2 circular subunits
found free in cytoplasm or attached to rough ER
make proteins
endoplasmic reticulum
stack of folded interconnected membranes
start at the edge of the nuclear membrane
rough-covered with ribosomes to make protein
smooth-make lipids
golgi aparatus
series of stacked, folded membranes (smaller than ER)
adds sugar to molecules
packages material for movement to another part of the cell or release from the cell (material is placed in a vesicle then moved elsewhere)
lysosomes
small, rounded, membrane-bound structures
contain digestive enzymes and other molecules to break down things ingested by the cell
vacuoles
membrane-bound bubble within a cell that stores something
mitochondria
kidney-shaped, contain highly infolded internal membranes called cristae
produce ATP
cristae
sides for metabolic enzymes to attach and function
chloroplasts
specialized structure for carrying out photosynthesis
contain chlorophyll
cytoskeleton
group of different protein strands- microtubules, microfilaments, and intermediate filaments
internal skeleton provides structure for cell
moves materials from place to place within the cell
moves the cell
nucleus
composed of nuclear membrane and chromosomes
nuclear membrane
membrane that surrounds the chromosomes
in it are nuclear pores (small holes that allow material to pass from the nucleus to the cytoplasm)
chromosome
strand of DNA and protein
exists in a highly coiled state- supercoiled
mitosis
occurs in somatic cells
diploid-2 chromosomes in pairs (2n)
replication of nucleus
phases: prophase, metaphase, anaphase, telophase, interphase
prophase
cell prepares to divide
nuclear membrane breaks down and the spindle apparatus forms
metaphase
the 2 sets of chromosomes line up in the middle of the cell
anaphase
the 2 sets of chromosomes move apart to opposite ends
telophase
the nucleus reforms and the spindle apparatus breaks down
interphase
period between cell mitosis
the cell cycle
phases a cell goes through
mitosis, growth, or DNA duplication
meiosis
occurs in reproductive cells (germ cells, sperm and egg)
haploid-single chromosome (1n)
cytokinesis
replication of the rest of the cell (cytoplasm and organelles)
cell metabolism
all of the various biochemical rections taking place in a cell
anabolism and catabolism
anabolism
building things up from smaller components or subunits
catabolism
breaking molecules down
enzymes
carry out all of the metabolic reactions in a cell
each is specific for a single reaction
catalyst
lower energy needed for the reaction to happen
substrate
the substance the enzyme acts upon
highly specific binding and depends on the shapes of the substrate and the enzymes active site
coenzyme
organic
needed by some enzymes to function
vitamins (fat soluble-A,E,D,K and water soluble-C and B)
cofactor
inorganic
mineral
needed by some enzymes to function
feedback inhibition
the amount of product produced is a signal that will shut down the enzyme
ATP
nucleotide used for energy transfer or short-term storage
transfer from places it’s made to places it’s needed
cleaving off one phosphate (ADP + P) releases energy
adding a phosphate restores energy
continually created and broken down in a cell
aerobic respiration
catabolism
glucose and oxygen are input to make CO2 and H2O (waste)
makes energy in the form of ATP
involves glycolysis, krebs cycle, oxidative phosphorylation, and respiration of proteins and lipids
glycolysis
catabolism
first step
glucose broken into 2 3-carbon acids (pyruvic acid)
2 ATPs are made
Kreb’s Cycle
catabolism
citric acid cycle
2 3-carbon molecules made from glycolysis are broken and released as CO2 and 2 ATPs
oxidative phosphorylation
catabolism
electron transport
majority of ATP made
in final step, H+ is added to oxygen and water is made
respiration of proteins & lipids
catabolism
all other molecules: proteins, lipids, and other carbs are fed into some stage of this pathway
anaerobic respiration
doesn’t require O2
use a different terminal acceptor in place of oxygen (sulfur or carbon)
fermentation
anaerobic respiration
involves glycolysis and other steps
DOES NOT go on the kreb’s cycle or electron transport chain
less efficient than aerobic, only produces 2 ATP and various organic end products
photosynthesis
anabolism
sun is source of energy used to build organic molecules
CO2 and H2O are input and O2 is waste
2 phases: light and dark reaction
light reaction
light is required
generates ATP
chlorophyll and accessory pigments are needed to trap the energy from different wavelengths of sunlight
water is split, protons passed through electron transport chain to generate ATP, oxygen is waste
dark reaction
calvin-benson cycle
light no required
ATP generated from light reaction is used with CO2 to make sugars and other molecules
chemosynthesis
unusual of anabolism
carried out by certain bacteria
photosynthesis without the sun
involves tapping into the energy of certain chemical reactions