midterm 1 (cell) Flashcards
cytoplasm
cytosol + organelles
organelles
organs of the cell
plasma membrane
tiny amphipathic membrane of lipids and proteins that contains the cytoplasm
amphipathic
both hydrophilic and hydrophobic parts
integral proteins
permanently attached to the membrane. can be transmembrane proteins or peripheral proteins
transmembrane protein
type of integral membrane that goes through the entire membrane
peripheral protein
type of integral membrane that is attached to the polar heads of the phospholipid bilayer (inside or outside of the cell), but they do not cross the membrane. helps support membrane
glycocalyx
sugary coating of cell membrane that allows for adherence to other tissues and acts as a cellular signature for recognition (white blood cells can recognize foregin cell)
characteristics of cell membrane
- membrane fluidity (from double bonds/kinks in the fatty acid tails)
- membrane permeability (selectively permeable)
- membrane gradients
diffusion
type of passive transport where molecules (both solvent and solute) move from high to low concentration
simple diffusion
non polar, hydrophobic substances move through the cell membrane (O2, CO2, nitrogen gases, vitamins DEAK)
facilitated diffusion
passive transport of molecules that are too polar or highly charged through cell membrane with help from specific transmembrane integral proteins
channel-mediated diffusion
integral protein ion channel allows for passage of specific small, hydrophilic, inorganic ions into a cell
carrier-mediated diffusion
passive transport of substances (glucose, galactose, fructose, vitamins) into the cell via carrier/transporter proteins. there is a transport maximum.
osmosis
net movement of a SOLVENT through a selectively permeable membrane via aquaporins. solvent moves from higher H2O concentrations to an area of lower H2O concentration, which equalizes the concentrations on either side of the membrane
hydrostatic pressure
pressure exerted by fluid at equilibrium due to the force of gravity. (equilibrium when there is an equal amount of H2O particles on either side of the membrane)
osmotic pressure
the pressure needed to be applied to a solute to prevent the solvent from passing through the membrane by osmosis. how much you need to push against membrane to stop H2O from coming back through
active transport
movement of polar and charged solutes AGAINST their concentration gradient. requires ATP energy and has a transport maximum.
primary active transport
pumps substance across plasma membrane against concentration gradient. Na+/K+ pump (Na+ out, K+ in)
secondary active transport
energy stored in Na+/H+ concentration gradients is used to drive other substances across membrane against their own concentration gradient (like holding the door open for someone)
antiporter
integral membrane protein involved in secondary active transport that carries 2 or more molecules in OPPOSITE directions through the cell membrane
symporter
integral membrane protein involved in secondary active transport that carries 2 or more molecules in the SAME direction through the cell membrane
endocytosis
active transport INTO the cell via a vesicle. can be receptor mediated, phagocytosis, or pinocytosis
exocytosis
active transport OUT of the cell within a vesicle. secretory vesicles from inside cell fuse with plasma membrane and release contents into extracellular fluid.
receptor-mediated endocytosis
requires specific ligands (molecules that bind to specific receptors) - membrane bows under the weight and forms a vesicle
phagocytosis endocytosis
pseudopods engulf large solid particles and pull them into the cell to be “eaten”
bulk-phase endocytosis/pinocytosis
small molecules dissolved in ECF are brought into the cell via vesicles (cell drinking)
transcytosis
through the cell. endocytosis starts on one side of the cell and undergoes exocytosis on the other side
cytosol
intracellular fluid that surrounds organelles. medium for chemical reactions within cells required for existence (ex. glycolysis)
cytoskeleton
network of protein filaments and microtubules that give structure to the cell
microfilaments
thinnest protein filaments found at edge of cell. involved in muscle contraction, cell division, wound healing in skin cells, providing mechanical support, microvilli support (intestinal cells)
intermediate filmants
protein filaments of the cell that stabilize the position of organelles. subject to mechanical stress
microtubules
largest protein filaments in the cell composed of tubulin. created in centrosome and allow for movement of organelles. make up cillia and flagella
organelles
organs of the cell. specialized structures that perform specific functions in cell growth, maintenance, reproduction. each has specific reactions and its own enzymes
centrosome
microtubule organizing centre. 2 centrioles @ a perpendicular angle. where the mitotic spindles grow which help things move around the cell during mitosis
cillia
type of microtubule used for cellular movement. like eyelashes that push things by the cell
flagella
type of microtubule used for cellular movement. like a tail (sperm)
ribosomes
protein factory - site of protein synthesis. found on rough endoplasmic reticulum, freely roaming, and mitochondria
endoplasmic reticulum (ER)
network of flattened sacs
rough ER
studded with ribosomes. processes and sorts proteins made from ribosomes. synthesis of phospholipids
smooth ER
synthesis of fatty acids and steroids. inactivates/detoxifies lipid-soluble drugs/potentially harmful substances
Golgi complex
Post office/quality control. Sorting, modifying, and packaging proteins, fats, etc. transport vesicles from ER dump proteins into the Golgi complex lumen, where enzymes modify the proteins into glycoproteins, glycolipids, and lipoproteins. Secretory vesicles deliver the modified proteins to plasma membrane. Alsodeliver by membrane vesicles.
Lysosomes
Stomach of the cell. Contains digestive and hydrolytic enzymes that break down molecules. Active transport pumps bring in h+. transporters more digested products into cytosol. Recycle cell structures.
Autophagy
Self-eating.
Autolysis
Self-destruction of entire cell. Occurs @ end of normal cell life cycle.
Perioxisomes
Peroxide bodies. Contain oxidases, enzymes that remove hydrogen. they oxidize amino acids and fatty acids, toxic substances (ex, alchohol)- oxidation leads to H2O2. Has enzymes that destroysuperoxide (free radical)
Proteasomes
Protein recycling centre. Breakdown of proteins into chunks. Destruction of cytosolic proteins.
Mitochondria
Powerhouses of the cell. make ATP through aerobic respiration. Muscles, liver and kidney cells have lots of mitochondria because they require lots of energy.more energy= more mitochondria. Plays a role in apoptosis. Have their own dna. Self-replicating.
Structure of mitochondria
External and internal mitochondrial membrane. Mitochondrial cristae (folds). Mitochondrial matrix (fluid filled cavity enclosed by the internal membrane, has ribosomes).
Nucleus
Oval spherical organelle that houses DNA. Nuclear pores in membrane control movement between nucleus and cytoplasm
Nucleoli
No membrane!!! Produces ribosomes. Prominent in cells that synthesize more protein (liver, muscle). disperse and disappear during cell division and reorganize once new cells are formed.
chromatin
how we store DNA when the cell is NOT dividing
chromosomes
condensed DNA - how we store DNA during cell division. DNA is coiled around histones (proteins)
centromere
centre of the chromosomes
chromatid
copy
centrosome
microtubule organization centre
protein synthesis
process of making proteins. happens in 2 parts: transcription (inside the nucleus) and translation (outside nucleus)
transcription
occurs in the nucleus. the process of making an RNA copy of a gene’s DNA sequence.
mRNA
messenger RNA is like the recipe/blueprint for protein synthesis. has a codon
rRNA
ribosomal RNA. joins with ribosomal proteins to make ribosomes
tRNA
transfer RNA. binds to amino acids and holds it in place on a ribosome. has an anticodon
steps of transcription
- RNA polymerase starts transcription at the promoter (start codon). 2. base pairs line up (A-U, G-C, C-G, T-A). 3. RNA polymerase runs down the DNA strand until it reaches the terminator codon. 4. pre-mRNA strand is left but snRNPS cut out introns, resulting in mature mRNA (alternative splicing). 5. mRNA passes through nuclear pore in nuclear envelope into cytoplasm
translation
carried out in the cytoplasm by ribosomes. mRNA is read and translated into amino acids (tRNA anticodon attaches to mRNA matching codon and then releases its amino acid)
apoptosis
cell death - genetically programmed and highly regulated
interphase
where the cell spends majority of its life cycle. G1 stage = growth, S phase is when DNA is synthesized, G2 stage = more growth and prep for mitosis
G1 phase (interphase)
centrosome replication begins, lots of cell growth
S phase (interphase)
DNA replication occurs
G2 phase (interphase)
replication of centrosomes is completed
mitotic phase
nuclear division and cytoplasmic division. distribution of 2 sets of chromosomes into 2 separate nuclei.
prophase (mitosis)
chromatin fibres condense. centromere holds the chromatid pair together. mitotic spindle attach to kinetochore. nuclear envelope breaks down, nucleus disappears.
metaphase (mitosis)
microtubules align centromeres in the middle of the mitotic spindle (metaphase/equatorial plate)
anaphase (mitosis)
centromeres split, separating chromatid pair. chromosomes move to opposite poles of the cell. cleavage furrow appears (makes the cell look like a peanut)
telophase
chromosomes uncoil and revert back to chromatin form. nuclear envelop forms around chromatin mass. nucleoli reappear. mitotic spindle breaks up. result is 2 genetically identical diploid cells
cytokinesis
cytoplasmic division (1 peanut cell splits into 2 separate cells). begins in late anaphase with formation of cleavage furrow and ends after telophase. contractile ring of actin microfilaments cleaves the cell in 2.
meiosis
occurs in the gonads (reproductive organs) and produces gametes (egg and sperm). results in 4 haploid gamete cells.
germ cell vs. gamete
germ cell is diploid (beginning cell for meiosis), gamete is haploid (result of meiosis)
prophase 1 vs. prophase (meiosis)
homologous chromosomes pair up to form a tetrad. crossing over occurs (exchange of genetic info).
metaphase 1 vs. metaphase (meiosis)
tetrads line up along metaphase plate, with pairs side by side
anaphase 1 vs. anaphase (meiosis)
tetrads are separated as paired chromatids still held together by centromere are pulled to opposite poles of the cell.
