Cell Biology Exam III

Where does glycolysis occur?

Cytoplasm

Where does the Krebs cycle occur?

In the mitochondrial matrix

Where does Oxidative Phosphorylation occur?

In the inner mitochondrial membrane

What are the three stages of catabolism?

1. Digestion
2. Glycolysis
3. Citric Acid Cycle

What does Kinase do in Glycolysis?

It transfers a phosphate group from ATP to a substrate in steps 1 and 3; other kinases transfer a phosphate to AFP to form ATP in steps 7 and 10

What does Isomerase do in Glycolysis?

Isomerase in steps 2 and 5 prepare molecules for the chemical alterations to come

What does Dehydrogenase do in Glycolysis?

The enzyme glyceraldehyde-3-phosphate dehydrogenase generates NADH in step 6

What does Mutase do in Glycolysis?

The movement of a phosphate by phosphoglycerate mutase in step 8 helps prepare the substrate to transfer this group to ADP to make ATP in step 10

Where are fatty acids degraded

The mitochondria

What is the result of each Citric Acid Cycle (Krebs Cycle)?

2 CO2 are released, and 3 NADH, 1 GTP, and 1 FADH2 are produced

What is used as precursors to various anabolic pathways?

Catabolism, intermediates of glycolysis and the citric acid cycle

What is glucose stored as in plants and animals?

* Starch → Plants
* Glycogen → Animals

Would you expect fatty acids to have odd or even numbers of carbon atoms?

Even (acetyl coA has 2 carbons)

Are the oxygen molecules that are consumed during the oxidation of glucose in animal cells the same ones as those in CO2?

No

How would you test the idea that oxygen molecules consumed during oxidation of glucose in animal cells are not the same as those in CO2?

Radioactive Isomers

What is the chemiosmotic hypothesis now referred as?

Chemiosmotic coupling

What does Glycolysis produce?

2 ATPs

What does oxidative phosphorylation do?

It uses O2 and produces ATP from ADP and inorganic phosphate

What is ATP Synthase?

A large protein complex that uses the proton gradient to drive the rotation of F0 complex

What has the highest redox potential?

Oxygen

What has the lowest redox potential?

NADH

What do light reactions absorb?

Chlorophyll absorbs blue and red light, but not green light

What occurs in Photosystem I?

Light produce electron flow that reduces NADP+ to NADPH

What does the water splitting complex do?

Provides the protons that restore the charge on the charge separated chlorophyll

What is the most abundant protein on earth?

Rubisco

What is the main function of the cytosol?

Contains many metabolic pathways; protein synthesis; the cytoskeleton

What is the main function of the nucleus?

Contains main genomes and RNA synthesis

What is the main function of the Endoplasmic Reticulum?

Synthesis of most lipids; synthesis of proteins for distribution to many organelles and to the plasms membrane

What is the main function of the Golgi apparatus?

Modification, sorting, and packaging of proteins and lipids for either secretion or delivery to another organelle

What is the main function of the lysosomes?

Intracellular degradation

What is the main function of the endosomes?

Sorting of endocytosed material

What is the main function of the mitochondria

ATP synthesis by oxidative phosphorylation

What is the main function of the chloroplasts?

ATP synthesis and carbon fixation by photosynthesis

What is the main function of the peroxisomes?

Oxidative breakdown of toxic molecules

Where are proteins synthesized?

In the cytoplasm

Proteins destined for the nucleus are produced in the cytoplasm and transported ___.

Through the nuclear pore complex

Proteins destined for various organelles are ___.

Directly transported across membranes

Proteins imported into the ER are ___.

Transported to various locations via vesicles

Oxidative phosphorylation is performed in this organelle.

Mitochondria

This organelle contains the main genome and is the location of DNA and RNA synthesis.

Nucleus

This organelle is the location of most lipid synthesis and synthesis of proteins for distribution to other organelles and secretion from the cell.

Endoplasmic reticulum

This organelle is the location of oxidative breakdown of toxic molecules.

Peroxisomes

This organelle sequesters (stores) calcium for release in cell signaling, like muscle contraction.

Endoplasmic reticulum

Prokaryotes function without membrane bound organelles. What is the advantage of having these functions?

Efficiency and specificity of organelles

Energy needed to drive nuclear import is provided by?

GTP

Smooth ER functions in ___.

Lipid biosynthesis, calcium sequestrations/release

Rough ER ___.

Is studded with ribosomes, where protein import occurs

Signal sequences are recognized by?

The signal recognition particle (SRP)

The signal sequence is eventually removed by a protease called___.

Signal peptidase

What is the best studied coat molecule that forms a basket-like cage?

Clathrin

What are the snare proteins and their functions?

Vesicle snare (v-snare) and target snare (t-snare) control proper targeting

Fluid and cargo is imported into the cell by ___.

Endocytosis

When large particles are engulfed the process is called ___.

Phagocytosis

What cells are specialized for phagocytosis?

Macrophages and neutrophils

Large membrane structures that engulf particles are called ___.

Pseudopods

What is used to degrade molecules?

Lysosomes

___ is the process of breaking down food molecules in successive steps.

Catabolism

NADH and FADH2 pass their high-energy electrons to the ___ in the inner mitochondrial membrane.

Electron Transport Chain

Chemiosmotic coupling is a mechanism that couples the synthesis of ATP with ___.

Membrane Transport of Protons

Numerous ___ are bound to the cytoplasmic face of the rough endoplasmic reticulum membrane.

Ribosomes

Receptor mediated endocytosis first internalizes cargo molecules via ___.

Clathrin coated vesicles

What are the types of cell signals?

Endocrine, paracrine, neuronal, and contact-dependent

What is Notch-Delta signaling (a type of contact-dependent signaling)?

Delta is expressed in a differentiation neuron, and this signal causes lateral inhibition of neighboring cells to prevent excess neuron differentiation

What is an example of a molecular switch used to prevent overstimulation in a signaling molecule?

Protein Kinases, GTP binding proteins, Monomeric G-proteins

What are the three types of cell surface receptors?

1. Ion-channel-coupled receptors
2. G-protein-coupled receptors
3. Enzyme-coupled receptors

What kind of signals do GCPRs receive?

Hormones, local mediators, neurotransmitters, odors, light, etc

Signaling that communicates locally, within a short distance through extracellular fluid is called ____ signaling.

Paracrine

Rapid signaling pathways mediate their signals via ___.

Altered protein function

G-protein-coupled receptor activation of phospholipase C ___.

Cleaves a phosphoinositol lipid to make IP3 and diacylglycerol

Growth factor receptor tyrosin kinases activate Ras, which leads to the activation of the ___ cascade.

MAP kinase

Signaling that communicates systemically, throughout the body is called ___ signaling.

Endocrine

The following happens when a G-protein-coupled receptor activates a G protein.

The alpha subunit exchanges bound GDP to GTP

What is an example given for molecular switches that toggle between off and on states?

Monomeric G protein

Adenylyl cyclase enzyme catalyzes the production of ___.

cAMP

Slower signaling pathways (1 hour or more) mediate their signals via ___.

Transcriptional mechanisms

The single-nucleotide polymorphisms found in the human population ___.

Can be linked into haplotype blocks

What are the three filament systems?

Intermediate filaments, actin, microtubules

What are the types and function of intermediate filaments?

* Keratin filaments, vimentin and related filaments, neurofilaments, nuclear lamins
* Enables cells to withstand mechanical stress and have great tensile strength

What is a tetramer?

the assembly subunit of the intermediate filament

What do microtubules do?

* Organize the organelles in the cytoskeleton
* Form the mitotic spindle
* Assemble into cilia and flagella

Which stage in the breakdown of glucose generates the most ATP?

Oxidative phosphorylation

The final metabolite produced by glycolysis is ___.

Pyruvate

Hexokinase catalyzes the first step of glycolysis that produces ___.

Glucose-6-phosphate

The electron transport chain converts high energy electron movements into ____.

Proton motive force

Where does oxidative phosphorylation take place?

Inner mitochondrial membrane

What is the role of molecular oxygen in the electron transport chain?

It is the ultimate electron acceptor

The photosystems in chloroplasts contain hundreds of chlorophyll molecules, most of which are part of ___.

The antenna complex

Name a component of the electron-transport chain that does not act as a proton pump.

Cytochrome c and ubiquinone

True or False. The ER membrane is contiguous with the outer nuclear membrane.

True

Where are proteins in the chloroplast synthesized?

In both the cytosol and the chloroplast

In which cellular location would you expect to find ribosomes translating mRNAs that encode ribosomal proteins?

Cytoplasm

The signal-recognition particle transiently binds the ___ and ___.

Signal sequence; ribosome

Receptor mediated endocytosis first internalizes cargo molecules via ___.

Clathrin coated vesicles

Which effect is likely to occur more rapidly in response to an extracellular signal? Changes in protein phosphorylation or changes in proteins being synthesized?

Changes in protein phosphorylation

Name the component in signal transduction?

(1) ligand (2) receptor (3) Signal transduction molecules (4) Effector proteins

G-protein-coupled receptor activation of phospholipase C next produces ___.

IP3 and diacylglycerol

Growth factor receptor tyrosine kinases activate Ras, which leads to the activation of the ___ cascade.

MAP kinase

From largest to smallest diameter, what is the correct order of cytoskeleton filaments?

Microtubules > Intermediate filaments > Actin

What is the nucleotide bound by actin?

ATP/ADP

What is the nucleotide bound by tubulin?

GTP/GDP