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Exam 2

Endo-membrane system

seperate structural and functional regions

Endo-membrane system

synthesizes proteins and lipids

Endo-membrane system

packaging and transport system

Endo-membrane system

sequestors toxic chemicals

Endoplasmic Reticulum

-membrane surrounding a lumen
-rough ER
-smooth ER
-rough ER and smooth ER often continuous

Rough ER

-contains many ribosomes for protein synthesis
-proteins are chemically modifies in lumen

Smooth ER

produces lipids and breaks down toxins

Golgi Complex

membranous sacs without ribosomes

Golgi Complex

chemical modification and packaging

Golgi Complex

regulates movement of many proteins

Golgi Complex

endocytosis of external susbstances

Lysosomes

membrane bound vesicle
-contains hydrolytic enzymes
-digestion and protection

Lysosomes

low pH
phagocytosis

Prokaryotic cells

-bacteria and archaea
-DNA
-Cytoplasm
-Plasma membrane
-Rigid Cell wall

Cytoplasm

location of most metabolic activity

Plasma membrane

little or no internal membrane structure

Eukaryotic Cells

-membrane-bound nucleus
-internal organelles
-protists, fungi, animals, and plants

Nucleus

-contains chromatin
-chromosomes
-nuclear envelope

Chromatin

mixture of DNA and protein

Chromosomes

one DNA molecule and associated proteins

Nuclear Envelope

nuclear pores open between both layers

DNA

codes for genetic traits

Cytoplasm

ions and organic molecules in aqueous solution

Plasma membrane

lipid bilayer surrounding the cell

Cell

-highly organized, water-based compartment
-filled with concentrated chemicals
-bounded by a thin flexible "membrane"

The Cell Theory

-all organisms are composed of cells
-the cell is the smallest "living" unit
-all cells arise from pre-existing cells

Mitochondria

Two membranes
-inner one is folded into cristae
-surrounds matrix
main function is ATP production
-"powerhouse" of the cell
-site of cellular respiration
-breakdown of organic molecules to produce
energy
-requires oxygen

Structures of plant cells

chloroplasts
central vacuoles
cell walls

Which organelle is the site of most of the cells protein synthesis?

cytoplasmic ribosomes

In which organelle are steroid hormones synthesized?

the smooth ER

How many membranes surround a chloroplast from a plant cell?

2

Which type of cytoskeletal protein is responsible for the movement of chromosomes during cell division?

microtubules

DNA strands can be visualized using which instrument?

electron microscope

The organelles and biomolecules present in homogenized cells can be separated by centrifugation. Which of the following would be found at the top of a centrifugation gradient?

ATP molecules

Which organelle is found only in plants?

glyoxysomes

The endomembrane system contains what?

the golgi apparatus and ER

The presence of _______ means that substances must pass through, rather than between, the epithelial cells that form the lining of the small intestine.

tight junctions

Nucleic acids are not found in...

plant vacuoles

The proteins that make up the cytoskeleton of bacteria are similar to ______ in eukaryotic cells.

actin

Which protein powers the movement of both cilia and vesicles within a cell?

dynein

Which organelle is involved in energy conversions?

chloroplasts

Some proteins that are on the surface of mammalian cells contain carbohydrates. These proteins are synthesized by ______ and the sugars added in the _______.

the rough ER and golgi apparatus

Plastids

present in nearly all plant cells

Microtubules

directly involved with the movement of organelles within a cell

A universal feature of receptors is that they

undergo structural (shape) changes when the signal molecule is bound.

In facilitated diffusion,

specific integral membrane proteins mediate transport.

cAMP is referred to as a

second messenger

Which of the following molecules do you think would diffuse across a phospholipid bilayer fastest, assuming that there are no proteins associated with the bilayer? [Hint: Keep in mind the nature of the interior of the bilayer.]

NH3

Hormones are chemical signals that

travel through circulatory systems.

The phosphorylation of proteins by ATP

is catalyzed by enzymes known as "protein kinases."

Caffeine

binds to receptors in the brain

The sodium-potassium pump (or Na+-K+ pump)

results in the formation of Na+ concentration gradient across the plasma membrane.

What would happen if a suspension of red blood cells in an isotonic NaCl solution was suddenly diluted with pure water by a factor of 10?

The cells would swell and lyse (burst).

Osmosis

the movement of water across membranes.

Phospholipids spontaneously form bilayer structures, but oils form small droplets. Why do oils not form bilayers?

Oils do not have the polar head group that phospholipids have.

In addition to the bilayer lipids and proteins, membranes may contain _______ in the form of _______ and _______.

carbohydrates; glycoproteins; glycolipids

Adenylyl cyclase

makes cAMP from ATP with the liberation of pyrophosphate (PPi).

Which step of the signal transduction cascade that results in glucose release during the "fight-or-flight" response does not directly involve a nucleotide?

Epinephrine binding to its receptor

Suppose the concentration of epinephrine in the blood stream of an animal drops. The cyclic AMP concentration in liver cells would be expected to _______ because _______ activity would _______.

decrease; adenylyl cyclase; decrease

In animals, cell recognition

involves proteins in plasma membranes.

Receptor-mediated endocytosis

results in the formation of clathrin-coated vesicles.

Chemical signal transduction pathways

involve binding of the signal molecule to receptors.

The mitochondrial ATP synthase

makes ATP at the expense of the proton gradient established by electron transport.

Reagents, such as dinitrophenol, increase the permeability of the mitochondrial inner membrane to protons. The addition of dinitrophenol to a suspension of animal cells should over the short term

inhibit mitochondrial ATP synthesis.

The ultimate source of energy for ATP synthesis in chloroplasts is

light

The major product of photosynthesis that is exported from the leaves to the rest of the plant is

sucrose.

In photosynthesis, NADPH is used for the

reduction of 3-phosphoglycerate (3PG).

Glycolysis

is an oxidation-reduction process.

The immediate source of energy for ATP synthesis in chloroplasts is

the electrochemical proton gradient.

Fermentation

results in the formation of lactic acid or ethanol.

The end products of glycolysis are

pyruvate, ATP, and NADH.

photosystem

a complex of pigments, proteins, and a reaction center chlorophyll

releases less energy than glycolysis

citric acid cycle

In green plant photosynthesis, water is

oxidized to oxygen gas (O2) in the light

The mitochondrial electron transport chain

oxidizes the intermediate electron carriers, NADH and FADH2.

Endergonic reactions are
A) nonspontaneous
B) spontaneous

nonspontaneous

absorption spectrum

A graph of light absorption versus wavelength of light; shows how much light is absorbed at each wavelength.

action spectrum

A graph of a biological process versus light wavelength; shows which wavelengths are involved in the process.

aerobic

presence of oxygen; requiring oxygen. (Contrast with anaerobic.)

anaerobic

Occurring without the use of molecular oxygen, O2. (Contrast with aerobic.)

carbon-fixation reactions

The phase of photosynthesis in which chemical energy captured in the light reactions is used to drive the reduction of CO2 to form carbohydrates

The catabolic pathways by which electrons are removed from various molecules and passed through intermediate electron carriers to O2, generating H2O and releasing energy.

cellular respiration

In photosynthetic light reactions, the flow of electrons that produces ATP but no NADPH or O2

cyclic electron transport

The anaerobic degradation of a substance such as glucose to smaller molecules such as lactic acid or alcohol with the extraction of energy.

fermentation

The biochemical synthesis of glucose from other substances, such as amino acids, lactate, and glycerol

gluconeogenesis

An organism that requires preformed organic molecules as food

heterotroph

ATP formation in the mitochondrion, associated with flow of electrons through the respiratory chain.

oxidative phosphorylation

A quantum of visible radiation; a "packet" of light energy.

photon

Regulation of the activity of a protein (usually an enzyme) by the binding of an effector molecule to a site other than the active site.

allosteric regulation

A transport protein in plant and animal cell membranes through which water passes in osmosis.

aquaporin

autocrine

A chemical signal that binds to and affects the cell that makes it

A compound formed from ATP that acts as a second messenger.

cAMP (cyclic AMP)

A process by which liquids or solid particles are taken up by a cell through invagination of the plasma membrane

endocytosis

A process by which a vesicle within a cell fuses with the plasma membrane and releases its contents to the outside

exocytosis

Passive movement through a membrane involving a specific carrier protein; does not proceed against a concentration gradient.

facilitated diffusion

A lipid to which sugars are attached.

glycolipid

A protein in which sugars are attached

glycoprotein

Any molecule that binds to a receptor site of another (usually larger) molecule

ligand

Pertaining to a chemical signal, such as a hormone, that acts locally, near the site of its secretion

paracrine

Diffusion across a membrane; may or may not require a channel or carrier protein

passive transport

Endocytosis by a cell of another cell or large particle.

phagocytosis

Endocytosis by a cell of liquid containing dissolved substances.

pinocytosis

The hydrostatic pressure of an enclosed solution in excess of the surrounding atmospheric pressure

pressure potential

An enzyme that catalyzes the addition of a phosphate group from ATP to a target protein.

protein kinase

Allowing certain substances to pass through while other substances are excluded; a characteristic of membranes

selectively permeable

Cell that is responsive to a particular type of physical or chemical stimulation.

sensory receptor cell

The series of biochemical steps whereby a stimulus to a cell (such as a hormone or neurotransmitter binding to a receptor) is translated into a response of the cell.

signal transduction pathway

An integral membrane protein that spans the phospholipid bilayer.

transmembrane protein

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