AP Bio Unit 4 (Google Classroom Slides)

What are the three types of cell signalling?

Direct contact, local signaling (short distance), long distance signaling (hormones)

What is direct contact signaling?

When cells transmit information to adjacent cells

What type of cells use direct contact signaling?

Immune cells

What is paracrine signaling?

When the chemical released from a cell acts on a neighboring cell

What is synaptic signaling?

A nerve cell releases neurotransmitter molecules into a synapse

What is autocrine signaling?

When a cell signals itself

What is long-distance (endocrine) signaling?

Signals sent long distances through the bloodstream, typically hormones

What are the three steps of cell communication?

Reception, transduction, response

What is the transduction step of cell communication?

A cell takes in a signal so that it can produce a response linked to it

What does signal transduction link?

Reception with response

What are four common cell responses?

Growth of cells, apoptosis, secretion of molecules, or gene expression

What chemical signal starts cell communication?

A ligand

How does a ligand initiate cell communication?

By binding to a specific receptor protein in a target cell (sent from a local or distant cell)

What can ligands be?

Small proteins (peptides) or a small molecule

What are G-coupled protein receptors (GPCRs)?

A type of receptor in eukaryotes in which a ligand binds and changes the shape of the receptor, which activates a G-protein by phosphorylation

What are kinases?

Enzymes that transfer phosphates from ATP (or GTP) to other molecules to activate them and relay a signal (phosphorylation)

What are phosphorylation cascades?

Events used in many transduction pathways in which phosphates are transferred between several kinases

What are second messengers?

Small molecules that can activate/amplify many pathways

What is cAMP?

A second messenger that is produced in large amounts and can activate many signal cascades

What are ligand-gated ion channels?

Ion channels that open or close when a ligand binds

What is gene expression?

What genes a cell makes its proteins with, and these genes can be turned on/off

What do cells differentiate based on?

Their gene expression

What is apoptosis?

Programmed cell death

What happens if one stage of signal transduction gets affected by a mutation or alteration?

Everything following that stage is affected as well

What do living things have to do ?

Maintain homeostasis

Why do cells need to adjust and adapt so that internal conditions are stable?

The external environment can't be controlled

What does homeostasis require?

Cellular communication and feedback

What is cellular feedback?

Cells' response to either amplify or counteract a stimulus based on input and output

What is negative feedback?

Reducing or counteracting a stimulus to return a system back to a set point

What is positive feedback?

Whenever a stimulus is amplified/moved further away from the original point

What is the cell-cycle?

The growth and reproductive cycle of a eukaryotic cell

What is interphase?

G1, S, and G2

What is the G0 phase?

When the cell is nondividing

What is the G1 phase?

Cell is active, duplicating organelles and growing

What is the S phase?

DNA is copied or replicated to form sister chromatids

What is the G2 phase?

Proteins are synthesized, ATP is produced, centrosomes are copied

What is the M phase?

Mitosis and cytokinesis; the cell is dividing

What is mitosis?

Type of eukaryotic cell division that transfers all of the cell's DNA to two genetically identical daughter cells

What is mitosis used for?

Growth, tissue repair, asexual reproduction

What are all of the phases of mitosis?

interphase, prophase, metaphase, anaphase, telophase, cytokinesis

What happens to sister chromatids in prophase?

They condense

What happens in relation to mitotic spindles in prophase?

They start to form

What do centrosomes do in prophase?

They move to opposite sides of the cell

What happens to the nuclear envelope in prophase?

It begins to break down

What happens to DNA during interphase?

It is uncondensed as chromatin

What is chromatin condensed into during prophase?

Chromosomes

What are sister chromatids?

Two identical chromosomes connected by a centromere

What happens to mitotic spindle fibers in metaphase?

They align the chromosomes along the equator of the cell

What happens to sister chromatids in anaphase?

They are split and pulled by spindle fibers in opposite directions toward the poles

What happens to the mitotic spindle fibers in telophase?

They break down

What happens to the nuclear membrane in telophase?

It reforms

What begins to divide in telophase?

The cytoplasm

What is formed during cytokinesis in animal cells?

A cleavage furrow

What is formed during cytokinesis in plant cells?

A cell plate

Why does the growth and reproduction of cells need to be regulated?

Cells can't divide too little or too much

What controls the progression through the cell cycle?

Signal transduction pathways known as checkpoints

What builds up as a cell proceeds through the cell cycle?

Cyclins

What happens if there are not enough cyclins during the cell cycle?

The cell does not advance to the next phase

What do concentrations of cyclins activate in the cell cycle?

Cyclin-dependent kinases

What do cyclin-dependent kinases do?

Allow the cell to advance to the next stage of the cell cycle

What happens if a checkpoint isn't function properly?

Apoptosis could occur to prevent tumor growth

What happens when checkpoints fail to regulate the cell, and apoptosis doesn't work?

Cells can turn into cancer

What is cancer?

Cells that divide uncontrolled