Cell Bio Midterm

what happens when O2 present in glycolysis

pyruvate converted to Acetyl-CoA (substrate for redox)

What are lipids?

fats and oils. soluble in non polar solvents. hydrophobic

What is a polysaccharide?

long polymer chain of monosacchraides joined together by glycosidic bonds (sugar)

what are proteins

polymers of amino acids

What is an unsaturated fatty acid?

One with double bonds (kinky)

What is a saturated fatty acid?

One without double bonds (not kinky)

what is TAG

triacylglycerol. made of 1 glycerol and 3 fatty acids

What is a phospholipid?

a lipid containing a phosphate group in its molecule. hydrophilic head and 2 hydrophobic tails. main component of membranes

What is a terpene?

type of lipids with an aromatic ring

example of disaccharide

sucrose, lactose, maltose

What do polysaccharides do?

energy storage and structural support

what are 2 polysaccharides that provide structure

cellulose (in plant cell walls) and chitin (in insect exoskeletons)

What is an amino acid?

organic compound containing both a carboxyl and an amino group.

What are the 4 levels of protein structure?

primary, secondary, tertiary, quaternary

What is the primary structure of a protein?

sequence of amino acids

What is the secondary structure of a protein?

region stabilized by H bonds between polypeptide back bone. alpha helix or beta pleated sheet

What is the tertiary structure of a protein?

3D structure including bending

What is the quarternary structure of a protein?

Overall structure when a protein is made up of two or more polypeptides

What are nucleotides made of?

5 carbon sugar, phosphate group, nitrogenous base

What are pyrimidines?

cytosine, thymine, uracil

what are the purines

Adenine and Guanine

how are nucleotides joined in DNA

phosphodiester bonds

What is transcription?

The process of making RNA from DNA via rna polymerase

What is translation?

Ribosome reads code from mRNA (in cytoplasm). Assembles amino acids into polypeptide chain

What is the central dogma?

DNA -> RNA -> Protein

What is the TATAA box?

A promoter region upstream from a gene. recognized by rna polymerase. rna polymerase 2 binds to TATA binding proteins to start transcription

what does nuclear pore complex do

controls movement of molecules in and out of nucleus. how mrna, proteins and ribosomes leave

how are nucleotides read by a ribosome

3 at a time (codon)

what are the ribosome subunit sizes

60s and 40s

what does the 60s ribosome subunit have

catalytic site where protein is made

what does the 40s ribosome subunit do

finds mrna and checks each codon with anti codon

what is trna and what does it do

Transfer RNA; tRNA brings appropriate amino acid into the ribosome and attaches it onto the growing polypeptide. has anticodon to check

which amino acid is the start codon

Methionine (AUG)

How are introns removed?

splicing carried out by a spliceosome to paste all exons together

What are adipocytes?

specialized fat cells that house triglycerides

What are acyltransferases?

catalyze the transfer of fatty acids from acyl CoAs to the 3 carbon unit. successive transfers give a triacylglycerol. TG is then stored in the lipid droplet

Where is TAG made?

Smooth ER. accumulates in lipid droplets

what are lipid droplets

Storage organelles that help to maintain the lipid and energy homeostasis. single layer membrane

What are perilipins?

coat proteins of lipid droplets

step 1 of lipid droplet formation

tag making enzymes and cholesterol ester making enzymes deposit neutral lipidsin between ER bilayer

step 2 of lipid droplet formation

sepin and other lipid droplet proteins form complex in ER side to grow lipid and push it out of membrane

step 3 of lipid droplet formation

lipid droplets bud toward cytoplasmic side. pushed by seipin. droplets grow by fusion or more tag synthesis

what is phosphatic acid

smallest phospholipid. removing a phosphate makes TAG.

where are enzymes that metabolize phospholipids found

membrane. not cytosol

how can phospholipids move within bilayer

rotate, move laterally (along same layer), transversely (from one layer to another)

what are translocases

proteins that move phospholipids between layers. maintains lipid asymmetry (flippase, floppase, scramblase)

what is frap

fluorescence recovery after photobleaching. method to study molecule mobility in cells by adding dye, bleaching an area, and watching other dyed molecules diffuse into area

integral membrane proteins

firmly embedded in the membrane

peripheral membrane proteins

proteins associated with but not embedded within the plasma membrane. make weak and reversible bonds to membrane by binding to integral proteins

lipid-anchored membrane proteins

sit on the surface of the lipid bilayer but are covalently bound to a lipid molecule

What do membrane proteins do?

detect and transmit signals, has receptors for chem signals, mediate cell-cell communication and adhesion

what are integral monotopic proteins

They are permanently embedded on the cell membrane from just one side.

what is glycosylation

Process of covalently attaching a carbohydrate to a protein or lipid

where can you find glycosylated proteins or lipids

outside membrane

types of passive transport

simple diffusion, facilitated diffusion, osmosis

types of active transport

primary and secondary

What is facilitated diffusion?

The diffusion of molecules across a membrane through transport proteins. glucose

how do solute carriers and ion channels differ

solute carriers have conformational change and are slower

what is a uniporter

carrier protein that transports a single solute at a time

what is a symporter

a carrier protein that transports multiple solutes in the same direction

what is an antiporter

two or more ions or molecules transported in opposite directions

what are porins

non specific channel proteins allow other molecules to move through the outer membrane. in mitochondria, chloroplasts, bacteria

why do k+ channels not let smaller na+ molecules through

na+ cant interact w oxygen due to size

why cant atp diffuse through membranes

negative charge

ways to move solutes against conc gradient

via ATP or electrochem gradient

What are the 4 ATPases for active transport

P-ATPase, Vacuolar-ATPase, F-type ATPases, ABC-type ATPases

P-ATPase

4 types. regulated by phosphorylation. maintains electrochem gradient

Ca2+/H+ ATPase

in SR or PM. In muscle cells. keeps Ca2+ conc in cytoplasm low

Na+/K+ ATPase

3 Na+ out per 2 K+ in per ATP. maintains Vm and Electrochem gradient

H+/K+ ATPase

enzyme responsible for pumping acid onto the mucosal surface of the stomach

what is a Vacuolar ATPase

2 rotary motors which turn axle and pump protons across the membrane to increase acidity. atp powered

What are F-type ATPases?

ATP synthases

H+ F-type ATPase

in inner mitochondrial membrane. uses H+ gradient to drive ATP synthesis. F0 is electric motor. F1 motor chem motor. both connected by stator

ABC-type ATPases

ATP binding cassette. mediates ATP powered movement of substrates across membrane. has 2 importers and 2 exporters to move big molecules. have hetero dimer

what is a heterodimer

2 different proteins that come together

where is ATP made in the mitochondria

matrix

What is an anabolic pathway?

make large molecules. endergonic (needs energy)

what is a catabolic pathway

breaks large molecules (exeergonic)

what is oxidation

loss of electrons

what is reduction

gain of electrons

What are NAD and FAD?

coenzymes of redox reactions. electron carriers. accept e-

What are coenzymes?

organic molecules that bind to active site of certain enzymes

what is a substrate of glycolysis

glucose and pretty much anything that ends in "-ose"

What kind of pathway is glycolysis?

catabolic - releases energy

What does glycolysis produce?

2 ATP, 2 NADH, 2 pyruvate

what happens in phase 1 of glycolysis

glucose phosphorylated twice and cleaved (needs ATP)

what happens in phase 2 of glycolysis

the 2 cleaved molecules are oxidized (2 ATP and 2 NADH made)

what happens in phase 3 of glycolysis

2 oxidized molecules converted into pyruvate (2 more ATP made)

What are disaccharides broken into?

monosaccharides (glucose, galactose, fructose)

What are monosaccharides turned into?

glycolysis intermediates

what happens when O2 present after glycolysis

pyruvate converted into Acetyl-CoA (substrate for redox)

what happens when O2 not present after glycolysis

pyruvate reduced to NAD+

where does glycolysis happen

cytoplasm

what does the mitochondrial pyruvate carrier do

transports pyruvate into mitochondria

Where does the TCA cycle occur?

mitochondrial matrix

What is the TCA cycle?

Krebs cycle (Citric Acid Cycle)

what happens in the krebs cycle

pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions

what is a dehydrogenase

an enzyme that removes a pair of hydrogen atoms from a substrate (oxidizes it)

What is the pyruvate dehydrogenase complex?

mitochondrial enzyme complex linking glycolysis and Citric Acid cycle

What does pyruvate dehydrogenase do?

converts pyruvate to acetyl-CoA. releases lots of energy. needs vitamin B1 as co-factor