cell and molec final combined flashcards

sorting signal/ signal sequence

a sequence of amino acids that directs a particular protein to a specfic destination in the cell

nuclear localization signal

a specific signal that allows proteins to be imported into the nuceluss, typically containing strectches of positively charged amino acids

Nuclear Import Receptor

A cytosolic protein that binds to the NLS of newly synthesized proteins and guides them to the nuclear pore.

Signal Recognition Particle (SRP)

A protein-RNA complex that recognizes and binds the ER signal sequence of a nascent polypeptide, directing it to the ER.

Co-translational Import

The process by which protein import into the ER occurs simultaneously with protein synthesis.

Protein Translocator

A membrane protein that facilitates the transport of proteins across membranes, such as into the mitochondria or ER.

Signal Peptidase

An enzyme that removes the signal sequence from a newly imported protein once it reaches its destination.

Vesicular Transport

A mechanism for transporting proteins by encapsulating them in vesicles that bud off from one membrane and fuse with another.

Free Ribosomes

Ribosomes that synthesize proteins in the cytosol and are not bound to any membrane.

Membrane-bound Ribosomes

Ribosomes attached to the ER membrane that synthesize proteins destined for secretion or for use within the cell's membranes.

Endomembrane system

A network of membranes within the cell, connected directly or via vesicular transport, including the nuclear envelope, ER, Golgi, endosomes, and lysosomes.

transmembrane proteins

Proteins that are partially translocated across the ER membrane, destined for organelle membranes or the plasma membrane.

ER signal sequence

A sequence of amino acids that directs proteins to the endoplasmic reticulum (ER) for translocation.

Start transfer sequence

A sequence of hydrophobic amino acids that initiates translocation of proteins into the ER.

Stop transfer sequence

An internal sequence within a protein that halts its translocation into the ER.

Vesicular transport

The process by which proteins and lipids are transported in vesicles between different compartments in the cell.

Clathrin

A protein that coats vesicles, helping to shape membranes into vesicles during vesicular transport.

Dynamin

A protein that assembles around the neck of a budding vesicle and employs GTP hydrolysis to facilitate vesicle detachment.

Glycosylation

A post-translational modification involving the attachment of oligosaccharides to proteins, commonly occurring in the ER.

Unfolded protein response (UPR)

A cellular response triggered by the accumulation of misfolded proteins in the ER, aiming to restore proper protein folding or trigger cell apoptosis.

Cisternal maturation model

A model explaining protein trafficking through the Golgi whereby cisternae mature and change as they move through the Golgi stack.

Constitutive exocytosis

A form of exocytosis that occurs continuously to deliver lipids and proteins to the plasma membrane and extracellular matrix.

Regulated exocytosis

A process where vesicles fuse with the plasma membrane and release their contents only upon receiving a specific signal.

Rab proteins

Monomeric GTPases that help direct transport vesicles to their specific target membranes.

SNAREs

Proteins that mediate the fusion of vesicles with target membranes, including v-SNAREs on vesicles and t-SNAREs on target membranes.

Protein quality control

The process by which the ER ensures that only properly folded proteins exit the ER, facilitated by chaperones.

Apoptosis

Programmed cell death, which may be triggered when misfolded proteins accumulate and the UPR fails to correct the issue.

Cargo receptors

Membrane-bound proteins that bind to specific cargo proteins and facilitate their transport in vesicles.

Oligosaccharide

A carbohydrate composed of a small number of monosaccharides, involved in the glycosylation of proteins.

Disulfide bonds

Covalent bonds formed between cysteine residues in proteins that help stabilize their structure.

Glycolysis

The process in which a molecule of glucose is broken down into two molecules of pyruvate, producing 2 ATP and 2 NADH.

Citric Acid Cycle

Also known as the TCA cycle or Krebs cycle, it is the stage where acetyl CoA is fully oxidized to CO2 and H2O, generating ATP, NADH, and FADH2.

NAD+

An oxidized form of nicotinamide adenine dinucleotide that serves as an electron carrier in cellular respiration.

Oxidative Phosphorylation

A process that uses a membrane-based mechanism to generate ATP, involving the electron transport chain and requires oxygen.

Substrate-Level Phosphorylation

A method of generating ATP directly during a metabolic pathway by transferring a phosphate group to ADP.

Pyruvate

A three-carbon compound that is produced from the breakdown of glucose during glycolysis.

Acetyl CoA

A two-carbon molecule that is produced from pyruvate and enters the citric acid cycle.

Fermentation

The process by which pyruvate is converted into lactate or ethanol when oxygen is scarce, regenerating NAD+.

The process by which pyruvate is converted into lactate or ethanol when oxygen is scarce, regenerating NAD+.

fermentation

Mitochondria

Organelles in which most energy from food molecules is harvested through cellular respiration.

Activated Carrier Molecules

Molecules like ATP, NADH, and FADH2 that transport energy or electrons within the cell.

Electron Transport Chain

A series of proteins in the inner mitochondrial membrane that facilitate oxidative phosphorylation.

Citric Acid Cycle Products

For each turn of the citric acid cycle, 3 NADH, 1 FADH2, 1 GTP, and 2 CO2 are produced.

GTP

a molecule similar to ATP that serves as an activated carrier of energy

Proton Gradient

An electrochemical gradient created across a membrane, crucial for ATP production during oxidative phosphorylation.

energy generation

phase during glyvolysis that produces ATP and high energy carriers

cellular respiration

the process by which cells convert food into energy through glycolysis, the citric acid cycle, and oxidative phosphorylation

Electron Transport Chain (ETC)

A series of electron carriers embedded in the inner mitochondrial membrane that facilitate electron transfer and generate a proton gradient.

Oxidative Phosphorylation

The process that uses energy from the oxidation of NADH and FADH2 to convert ADP to ATP

Chemiosmotic coupling

the linking pf chemical bond- forming reactions that synthesize ATP with membrane trasnport processes that pump protons

proton gradient

a difference in proton concerntation across a membrane, generated by the electron transport chain that drives ATP synthesis

ATP synthase

an enzyme that synthesizes ATP from ADP and inorganic phosphate, using the energy from the proton gradient

Acetyl CoA

a molecule that is produced in the mitochondira and further oxidized to CO2 during cellular respiration generating high energy electrons

role of oxygen in cellular respiration

oxygen acts as final electro acceptor in the electron trasnport chain, allowing for the continuation of the process

mitochondrial matrix

the innermost compartment of mitochondria where the citric acid cycle occurs and is rich in enzymes for oxidation of pyruvate and fatty acids

intermembrance space

the space between the inner and outer membranes of the mitochondria, containing enzymes that utlize ATP for phosphorylation

final electron acceptor

oxygen is the final electron acceptor in the electron trasnport chain, essential for oxidative phosphorylation

vesicular trasnport

vesicle formation/ cargo selection

vesicle docking

vesicle function

vesicle formation

vesicles have a distinct protein coat on their cytosolic surface

protein coat has two function

to help shape the membrane into a “bud”

helps capture molecules for onward trasnport

clathrin- coated vesicles

transport materials between the Golgi and the cell surface, as well as endocytosis, by forming a basket-like structure that aids in vesicle budding.

dynamin coated vessicles

A GTPase enzyme that pinches off vesicles from the membrane during endocytosis, facilitating vesicle release.

cis golgi network

The entry point of the Golgi apparatus where proteins and lipids are received from the endoplasmic reticulum, facilitating their processing and sorting for transport to various destinations.

trans golgi network

The exit point of the Golgi apparatus that modifies and sorts proteins and lipids before they are sent to their final destinations, including secretion outside the cell or delivery to lysosomes.

endocrine

hormones

signal is widely distributed

paracrine

local mediators

neuronal

neurotrasnmitters

takes place over long distance

signalling is very fast and very specific

contact dependent

membrane bound signal molecules

very short distance

large/ and or hydrophillic

most signals

bind to cell surface receptors

binding event generates an intracellular signal

receptor relays the info across the PM

small and / or hydrophobic

few signals

cross plasma membrane and enter cells

bind to intracellular receptors

Organelle required for the synthesis of secreted proteins.

endoplasmic reticulum

Organelle involved in degrading old unneeded proteins.

lysosome

Cell component that does not contain DNA

Golgi apparatus

Cell component that consists of protein filaments that give a cell shape

cytoskeleton

Which of the following molecules would not form hydrogen bonds?

a. CH3OH

b. CH3OCH3

c. CH3COOH

d. NH3

e. H2O

b. CH3OCH3

Formation of a hydrogen bond requires two _________ bonds.

Polar Covalent

Proteins are composed of ________

Amino Acids

What functional group is created when amino acids are joined together through peptidebonds?

amide

For a cytosolic protein _________ amino acids tend to be found in the interior of the proteinand __________ amino acids tend to be present on the exterior of the protein

nonpolar, polar

Which of the following statements describes a covalent bond between carbon and hydrogen?

a. The electrons are shared equally between the two atoms of the bond.

b. The electrons of the bond are pulled closer to the nucleus of hydrogen

.c. The electrons of the bond are pulled closer to the nucleus of carbon.

c the electrons of the bond are pulled closer to the nucleus of carbon

Which of the following molecules can form hydrogen bonds?

a. CH4

b. CH3OCH3

c. CO2

d. NH3

d. NH3

Which of the following molecules contains only nonpolar bonds?

a. CH4

b. H2O

c. NaCl

d. NH3

a. CH4

Type of noncovalent interaction between an acidicamino acid and a basic amino acid within aprotein.

a. hydrogen bonds

b. van der Waals attractions

c. electrostatic attractions

d. hydrophobic forces

d. hydrophobic forces

All of the following are functions of cellular proteins except

:a. act in signaling between cells

b. transport ions and polar molecules into and out of cells

c. perform enzymatic reactions

d. store the genetic information of a cell

e. regulate gene expression

d. store the genetic information of a cell

Amino acids are joined together to form polypeptides. Each amino acid is attached to another by a peptide bond. What functional group is created when amino acids are joined together?

a. ketone

b. amide

c. ester

d. carboxylic acid

b. amide

A peptide bond is ______.

a. rigid

b. planar

c. a covalent bond

d. all of the above

D. all of the above

Which of the following statements about proteins is false?

a. The amino terminus has a free NH3+ group

.b. The carboxy terminus has a free COO- group.

c. The polypeptide backbone looks the same for all proteins.

d. The order of amino acids in a protein is the same for all proteins.

d. The order of amino acids in a protein is the same for all proteins.

What would be left after treating a protein with a compound that destroys noncovalent interactions?

a. a protein with a folded stable 3D shape

b. an unfolded polypeptide chain

c. a protein with an altered folded shape

d. amino acids

b. an unfolded polypeptide chain

Aquaporins are water channels located within the plasmamembrane. These proteins span the lipid bilayer of the plasmamembrane and have an internal pore through which watermolecules can enter or leave the cell. Which of the following wouldbest describe this protein?

a. Aquaporins have a nonpolar pore with a nonpolar outer layer.

b. Aquaporins have a polar pore with a polar outer layer.

c. Aquaporins have a polar pore with a nonpolar outer layer.

d. Aquaporins have a nonpolar pore with a polar outer layer.

c. Aquaporins have a polar pore with a nonpolar outer layer.

Which of the following is an example of secondary structure?

a. random coil

b. beta sheet

c. double helix

d. coiled-coil

b. beta sheet

In an alpha helix, the R groups on the amino acid residues_________.

a. alternate between the outside and the inside of the helix

b. are found on the outside of the helix

c. generate the hydrogen bonds that form the helix

d. stack within the interior of the helix

b. are found on the outside of the helix

Which of the following is responsible for secondarystructure within a protein?

a. Peptide bonding between amino acids

b. Hydrophobic interactions

c. Hydrogen bonding between amine groups and carbonyl groups

d. Hydrogen bonding between R groups/side chains

c. Hydrogen bonding between amine groups and carbonyl groups

In a coiled coil, _________ amino acids are buried at the interface between two alpha helices.

a. positively and negatively charged

b. uncharged polar

c. nonpolar

c. nonpolar

The amino acid sequence Ala-Gly-His-Tyr is anexample of which level of protein structure?

a. Tertiary

b. Quaternary

c. Secondary

d. Primary

d. Primary

A protein corresponding to a single polypeptide chain does not have ___________ structure.

a. primary

b. secondary

c. tertiary

d. quaternary

d. quaternary

Disruptions of hydrogen bonds could alter which of the following levels of protein structure.

a. primary, secondary, tertiary, and quaternary structure

b. only secondary, tertiary, and quaternary structure

c. only tertiary and quaternary structure

d. only quaternary structure

b. only secondary, tertiary, and quaternary structure

Proteins often have regions that show specific, coherent patterns of folding and function. These regions are called:

a. subunits

b. active sites

c. domains

d. binding sites

c. domains

The term "denaturation," when used in conjunction withproteins, refers to a change in structural characteristicsprimarily due to __________.

a. changes in primary structure

b. the binding of toxic compounds

c. the disruption of non-covalent bonds

d. the disruption of covalent bonds

c. the disruption of non-covalent bonds

Protein S will fold into its native conformation only when protein Q isalso present in the solution. However, protein Q can fold into its nativeconformation without protein S. Protein Q, therefore, may function asa ____________ for protein S.

a. chaperone

b. subunit

c. cofactornative

(conformation: folded shape of a protein)

a. chaperone

A nucleosome contains two molecules each of histones_________.

a. H1,H2, H3 and H4

b. H1, H2A, H2B and H3

c. H2A, H2B, H3 and H4

d. H2, H3, H4 and H5

c. H2A, H2B, H3 and H4

Protein required for formation of the chromatin fiber.

a. histone H2A

b. histone H1

c. cohesins

d. CAP

b. histone H1