Unit 2 Flashcards by Nick Eaton

What happens during G0? What comes after it?

Normal specialized cell functions happen during G0 phase. When mitogens are introduced the cell enters interphase at the G1 phase.

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What happens during G1? What stages come before and after it?

G1 is a period of cell growth, protein synthesis, and organelle duplication/ production. G1 is a stage of interphase with G0 coming before and the S stage coming after.

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What happens during the S stage? What stages come before and after it?

The S stage is the period which DNA is replicated (makes a copy of every chromosome - DNA remains in the chromatin state), and histones are synthesized. It is a part of interphase with the G1 stage coming before and the G2 stage coming after.

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What happens during the G2 stage? Which states come before and after?

G2 is a period of more growth, protein synthesis, and DNA begins to condense. S stage comes before and prophase comes after.

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The largest portion of the cell cycle, when a parental cell is growing in preparation for division, synthesizing all necessary proteins for that task, and duplicating all of its DNA molecules, is called _______.

interphase

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A region of DNA that contains the information needed to make one or more functional proteins is called a ______.

gene

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Regulatory proteins that bind to DNA at the promoter region and either activate or inactivate the expression of a gene are called _____.

transcription factors

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This process occurs when the DNA base sequence is used to make a complementary piece of RNA, specifically called pre-mRNA.

transcription

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In what part of the cell is a section of DNA copied into RNA?

nucleus

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This enzyme separates the two strands of the DNA double-helix at a specific gene and synthesizes a complementary strand of RNA.

RNA polymerase

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This is the specific kind of RNA that is complementary to a gene coded in DNA and is ultimately read by ribosomes to create the protein.

mRNA

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______ are noncoding segments of an immature or pre-mRNA molecule that are removed during alternative splicing (or mRNA processing) to convert pre-mRNA into mature mRNA.

introns

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______ is the extracellular fluid of your erythrocytes, leukocytes, and
thrombocytes.

Plasma

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______ is the extracellular fluid that surrounds body tissue cells.

Interstitial fluid

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______ is the fluid inside body cells where the nucleus, organelles, and
inclusions are suspended.

Intracellular fluid

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_______ is defined as the passive movement of molecules from an
area of higher concentration to an area of lower concentration of
those molecules.

Diffusion

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There is a very specific term for the passive movement of water across the plasma membrane to maintain osmotic equilibrium. That term is _____.

osmosis

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There are two types of membrane transporters. This sub-type is a
water-filled passageway that directly links the extracellular and
intracellular compartments. These membrane transporters also ONLY
allow for passive transport of ions.

Channel proteins

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This sub-type of membrane transporter binds to its substrate(s) on one side of the plasma membrane, changes conformation, and transports it/them through to the other side, but never forms a direct connection between the intracellular and extracellular compartments. These membrane transporters can also do either passive or active transport.

carrier proteins

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If molecules move through the plasma membrane via membrane transporters, move down their concentration gradient, and net transport stops when the concentrations are equal on both sides of the
membrane, the process is specifically known as _____________.

Facilitated diffusion

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During alternative splicing or mRNA processing, some sections of the pre-mRNA molecule are kept and spliced together to form the mature mRNA molecule. These sections that are kept and spliced together are called ______.

exons

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If molecules move through the plasma membrane via membrane transporters, move against their concentration gradient, and ATP is needed as an energy source, this process is known as ___________.

Active transport

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This is the name of the process where mature mRNA directs the assembly of amino acids into a polypeptide or protein.

translation

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_________ channels or pores spend most of their time with their gate
open, allowing ions to move back and forth across the membrane
without regulation.

Open

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________ channels spend most of their time closed, but can be opened under specific conditions then they allow the movement of ions across the plasma membrane.

Gated

These channels will change conformation and open when the electrical state of the cell reaches a specific level.

Voltage-gated

Where a mature mRNA molecule is read to create a new protein chain, happens at these intracellular inclusions.

ribosomes

These channels must bind an intracellular or extracellular signal molecule to change conformation and become open.

Chemically-gated

A triplet of mature mRNA bases that codes for a specific amino acid is called a ______.

codon

If a carrier protein moves two or more types of solutes in opposite directions, it is specifically called an ________ carrier.

Antiport

_____ is the molecule that delivers a specific amino acid to the ribosome during translation so it can be attached to the growing polypeptide or protein.

tRNA

If a carrier protein moves two or more types of solutes in the same direction, it is specifically called a ______ carrier.

Symport

If a membrane channel opens, Na+ ions would flow (into or out of) the cell.

Into

If a membrane channel opens, K+ ions would flow (into or out of) the cell.

Out of

A triplet of nucleotide bases called a(n) __________ that binds to a complementary trio of bases on the mature mRNA molecule.

anticodon

If a membrane channel opens, Cl- ions would flow (into or out of) the cell.

Into

If a membrane channel opens, Ca2+ ions would flow (into or out of) the cell.

Into

Proteins are not usually in their final or mature form when they are first produced. They typically must undergo ________ within the lumen of the rough endoplasmic reticulum, where they fold into complex shapes, may be split by enzymes into smaller peptides, or have various chemical groups added to them.

post-translational modification

mRNA does not last forever. Cells need to have control over protein synthesis after all. When mRNA is no longer needed, it is broken down by a class of enzymes called ____.

ribonucleases

The smaller portion of cell cycle, when the duplicated parental chromosomes are separated and passed to the new daughter cells, and the cytoplasm of the parental cells divides, is called ______.

mitosis

When human body cells divide out of control, a disease broadly referred to as _____ can arise, where groups of these defective cells accumulate into a mass or migrate throughout the body, ultimately interfering with normal physiological mechanisms.

cancer

The electrical gradient (difference) between the extracellular fluid and the intracellular fluid is known as the ____________.

Membrane potential

During this sub-phase of Interphase, a cell will duplicate all its DNA molecules (chromosomes) so that each daughter cell gets a full complement of genetic instructions.

S phase

For nerve and muscle cells, the inside of the cell is more _________ charged relative to the outside.

negatively

There are points in the cell cycle called _______ where the cell determines if its DNA is healthy and if it has enough resources to divide successfully.

checkpoints

If Cl- ions diffuse through an ion channel, the inside of the cell becomes __________, meaning it becomes more negatively charged than before.

Hyperpolarized

If Na+ ions diffuse through an ion channel, the inside of the cell becomes __________, meaning it becomes more positively charged than before.

Depolarized

When a cell determines that it cannot fix an error in its DNA and cannot complete its cell cycle successfully, it will usually undergo a process called _______ where it will self-destruct.

Apoptosis

If those Na+ channels close and K+ channels open, the charge inside the cell would return to its resting state or it would become ______.

Repolarized

_________ is a general term for a molecule secreted by a cell into the extracellular fluid and detected by specialized receptors elsewhere in the body.

Chemical signals

A ______ has specialized receptor proteins to detect the presence of chemical signals.

Target-cell

Many cells in your body are currently in resting phase and performing their specialized function. They are not currently dividing nor preparing to divide at all. These cells are said to be in _____.

G0 phase

The simplest form of cell-to-cell communication is the direct transfer of electrical or chemical signals through _________, which are protein channels that create cytoplasmic bridges between adjacent cells.

Gap-junctions

Cells can also communicate via the surface molecules on one cell membrane binding to a membrane receptor on another cell. Cell adhesion molecules (CAMs) are an example. This process is called ______.

Contact-dependent signaling

When two identical DNA molecules are condensed and held together at a centromere, this “X-shaped” structure is most specifically called a ________.

sister chromatid

A(n)_______ signal is a chemical that acts on cells in the immediate vicinity of the cell that secreted the signal.

Paracrine

This is the most specific term for one molecule of DNA that has been condensed into a “log-like” structure prior to cell division.

chromatid

A(n) _______ signal is a chemical signal that acts on the same cell that secreted it.

Autocrine

This is the most specific term for a DNA molecule that is not fully condensed, but only loosely wrapped around small proteins called histones. It appears like a “beads on a string”.

chromatin

This is a chemical signal that is secreted by specialized cells into the blood and is then distributed all over the body by the circulation.

Hormone

During this sub-phase of mitosis, sister chromatids split apart, allowing spindle fibers to pull individual chromatids towards opposite poles of the cell.

Anaphase

If a neuron secretes a signal molecule into the blood stream for distribution, it is called a _________.

Neurohormone

During this sub-phase of mitosis, the individual chromatids arrive at opposite poles of the dividing cell and new nuclei form around them.

Telophase

If a neuron secretes a signal molecule that binds to receptors on a nearby neuron and that event has a rapid and short-lasting effect on the target cell, that signal is called a _________.

Neurotransmitter

During this sub-phase of mitosis, the sister chromatids are fully condensed and visible. Spindle fibers begin to extend from opposite poles of the cell and the nucleus is dissolved by the end of this sub- phase.

Prophase

If a neuron secretes a signal molecule that binds to receptors on a nearby neuron and that event has slow or prolonged effect on the target cell, that signal is called a ____________.

Neuromodulator

During this sub-phase of mitosis, the sister chromatids attach to spindle fibers and all line up at the center of the cell in a single-file line.

Metaphase

This type of signal molecule can be produced by almost any cell in the body, travels through the blood, and is particularly important in immune system communication.

Cytokine

This is the technical term for the dividing of the cell and its cytoplasm during mitosis. This process starts during Anaphase and finishes at the end of Telophase.

Cytokinesis

The transmission of information from one side of the membrane to the other using membrane proteins is called ___________.

Signal transduction

When a signal molecule binds to this kind of receptor, a change occurs within the intracellular cytoskeleton.

Integrin receptor

When this kind of receptor is activated by a signal molecule, the receptor will activate an intracellular enzyme to which it is physically attached.

Receptor enzyme

This kind of receptor has seven membrane-spanning regions. When it binds its signal molecule, it can open an ion channel or alter the activity of intracellular enzymes like phospholipase C.

G-protein coupled receptor

For this kind of receptor, binding a ligand opens or closes the channel and changes the flow of ions across the membrane.

Receptor channel

In general, diffusion is faster when... (4 things)

Diffusion is faster - along higher concentration gradients - over shorter distances - at higher temperatures - for smaller molecules

Simple diffusion is faster if... (4 things)

- the membrane's surface area is larger - the membrane is thinner - the concentration gradient is larger - the membrane is more permeable to the molecule

During simple diffusion, the membrane permeability to a molecule depends on... (3 things)

- the molecule's lipid solubility - the molecules size - the lipid composition of the membrane

Chemical and electrical disequilibrium must be maintained at rest by ______ for proper cell function

Membrane transporters

Usually, water moves freely through the membrane or through specialized water channels called ______.

aquaporins

Substances like _____ or ______ CANNOT move freely through the cell membrane. What do they require to facilitate their movement through the membrane?

Ions or polar molecules. They require a membrane transporter.

Describe channel proteins. What uses channel proteins? Describe what substances move through the channel based on.

Fluid-filled, tunnel-like passageways. Used ONLY for ions and water. Move based on concentration and/or electrochemical gradient. Passive, facilitated diffusion when open.

Describe open channels and their alternate names. What do they allow?

They are open most of the time; only occasionally closed. Also called “leak channels” or “pores”. They allow free-flow of substances via facilitated diffusion through them, into or out of cell, when open.

Describe gated channels. What is their function?

Gated channels need a trigger/ stimulus to open or close. They are necessary to regulate or control movement of *ions* into or out of cell based on a cell’s needs at any given moment.

What are the 3 types of gated channel proteins?

1. Voltage-gated 2. Chemically-gated 3. Mechanically-gated

What is the stimulus that changes the permeability of a voltage-gated channel protein?

To change permeability in response to a change in the cell’s membrane potential.

What is the stimulus that changes the permeability of a chemically-gated channel protein?

Change permeability in response to a chemical stimulus (e.g., ligand binds to receptor)

What is the stimulus that changes the permeability of a mechanically-gated channel protein?

Changes permeability in response to pressure or temperature changes

What do monovalent cation channels allow to enter and leave the cells?

Allow Na+ to enter and K+ to leave cells

Name the sequence of events used by carrier proteins during facilitated diffusion.

-open to one side -substrate binds to high affinity binding site - carrier changes shape and opens a passageway to other side of membrane - substrate dissociates because the binding site switches to low affinity in this new configuration -repeat

True or False: Carrier proteins never form an open channel between the two sides of the membrane.

True

What do carrier proteins move across the cell membrane? Give some specific examples

Ions and charged, polar, or large molecules that can't fit through a channel. Ex: glucose, amino acids, peptides, ammonia, nitrogenous wastes.

Name two carrier proteins that are glucose transporters

GLUT-2s and GLUT-4s

Describe the uniport carrier protein by the number and direction of substances moving through them.

UNIport carriers transport only ONE kind of substrate.

Describe the symport carrier proteins by the number and direction of substances moving through them.

Symport carriers move two or more substrates in the same direction across the membrane.

Describe the antiport carrier proteins by the number and direction of substances moving through them.

Antiport carriers move substrates in opposite directions.

The nucleotides in one strand are oriented with their

3' carbon facing up and 5' carbon facing down

During active transport which direction are substrates moved?

against their concentration gradient

Where does translation occur?

At the ribosome floating in cytosol or on rough endoplasmic reticulum

cross-linkage creates...

strong covalent bonds

during the cell cycle, the cell will spend about 90% of its time during this phase

Interphase

During this phase of mitosis, sister chromatids separate, pulled by spindle fibers

Anaphase

During this phase of mitosis, chromatids arrive at opposite sides of cell, new nuclear envelopes form, DNA uncoils into chromatin, chromosomes/ chromatin are no longer visible

Telophase

What are the 3 types of active transport?

Primary, secondary, and vesicular

Why is primary active transport called "primary"?

because energy from ATP is used at the site of transport or exchange

Where does post translational modification occur?

within the lumen of the rough ER for only some proteins

What enzyme creates pre-mRNA for the DNA template?

RNA polymerase

What does RNA polymerase do?

-Unzips DNA to expose correct gene -Catalyzes the reaction that builds a complementary mRNA strand from free ribonucleotides

What is a snRNPs?

a group of small nuclear ribonucleoproteins that combine to form a spliceosome

Define a splicosome.

This is the enzyme used to edit mRNA.

after modification in the rough ER, proteins travel to the...

golgi complex for sorting and packaging

Replication occurs by unzipping and duplicating each DNA parent strand by these two enzymes.

DNA helicase and DNA polymerases

This is the enzyme that breaks hydrogen bonds between complementary bases to unzip double helix

DNA helicase

This is the enzyme that inserts and binds free nucleotides that match the DNA parent strand bases

DNA polymerase

These are small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.

Okazaki fragments

Name the 3 types of passive transport.

osmosis, simple diffusion, facilitated diffusion

This type of transport does not require energy from ATP and moves substances down a concentration gradient from high to low

passive transport

Explain how Na+/K+-ATPase works step by step.

1. 3 Na + from ICF bind to high-affinity sites 2. ATPase is phosphorylated with Pi from ATP 3. Protein changes conformation (opens to the ECF) 4. Na-binding sites lose their affinity for Na+ and release 3 Na+ into ECF 5. High-affinity binding sites for K+ appear 6. 2 K+ from ECF bind to high-affinity binding sites 7. Pi released 8. Protein changes conformation (opens to the ICF) 9. K-binding sites lose their affinity for K+ and release 2 K+ into ICF 10. High-affinity binding sites for Na+ appear. Repeat

This type of transport requires energy from ATP and moves substances against a concentration gradient from low to high

active transport

This type of transport is handled by carrier proteins, and moves all solutes against the concentration gradient powered by ATP

primary active transport

This type of transport is handled by carrier proteins, which move at least one solute down the concentration gradient, and the other solute moves against the concentration gradient, powered by ion concentration gradients

secondary active transport

Why is secondary active transport called secondary?

Does not use (hydrolyze) ATP at the site of transport. Depends on energy from primary active transport.

When protein-mediated transport reaches its point of saturation it is known as the ______.

transport maximum

Unit 2 Flashcards

(122 cards)