Question 1

What is the relationship between insulin and glucagon in homestasis?

Accepted Answer

When blood glucose is too high, insulin is released to lower it by storing it as glycogen

When blood glucose is too low, glucagon is released to increase it by releasing glucose from storage

Question 2

What is the relationship between calcitonin and PTH in homeostasis?

Accepted Answer

If blood calcium is too high, calcitonin is released by the thyroid to decrease calcium levels by turning calcium into bone and decreasing absorption by intestines + kidneys

If blood calcium is too low, PTH is released by the parathyroid to increase calcium levels by taking calcium from bones and increasing absorption by intestines + kidneys

Question 3

What is binary fission?

Accepted Answer

The process of prokaryotes dividing

The prokaryote elongates until it is double its size, then pinches in and separates into two identical daughter cells

Question 4

What is the cell cycle?

Accepted Answer

A series of events that takes place in eukaryotic cells as they grow and eventually divide

Question 5

What are the four main stages of the cell cycle?

Accepted Answer

G₁, S, G₂ , and M

Question 6

What is the G₁ phase in the cell cycle?

Accepted Answer

First growth phase where the cell grows larger, copies organelles, and makes molecular building blocks it will need later

Question 7

What is the S phase in the cell cycle?

Accepted Answer

Second stage of the cell cycle where the cell creates a complete copy of its DNA in its nucleus

(also duplicates the centrosome, which helps separate DNA during the M phase)

Question 8

What is the G₂ phase?

Accepted Answer

Third stage of the cell cycle where the cell grows more, makes proteins and organelles, and begins to reorganize itself to prepare for mitosis

Question 9

What is the M phase?

Accepted Answer

The final stage of the cell cycle where the cell divides its DNA and cytoplasm to make two new cells

(two phases: mitosis and cytokinesis)

Question 10

What is interphase in the cell cycle?

Accepted Answer

The first three stages (G₁ phase, S phase, and G₂ phase) that are in between the previous M phase and the next

Question 11

How long does it take for a cell to go through the cell cycle?

Accepted Answer

Varies based on the type of cell

(skin cells go very quickly, whereas nerve cells don't go through it at all as they are amitotic)

Question 12

What is chromatin?

Accepted Answer

The material that makes up chromosomes and is made of RNA and DNA

(exists in all organisms other than bacteria)

Question 13

What is prophase?

Accepted Answer

First phase of cell division where the chromosomes condense, the mitotic spindle starts to form, and the nuclear envelope breaks down

Question 14

What is metaphase?

Accepted Answer

Second stage of cell division where the sister chromatids line up in the middle of the cell and prepare to split apart

(line up at the metaphase plate)

Question 15

What is anaphase?

Accepted Answer

Third step of cell division where the sister chromatids move via the microtubules to opposite poles of the cell, leaving each pole with a complete set of chromosomes

Microtubules push the poles apart

Question 16

What is telophase?

Accepted Answer

Fourth phase of cell division where the cell is nearly done dividing and the cell starts to re-establish its normal structures

(miotic spindle is broken down; two new nuclei form for each set of chromosomes; chromosomes decondense)

Question 17

What is cytokinesis?

Accepted Answer

The division of cytoplasm during M phase to create two new cells

(creates a cleavage furrow in animal cells using a "drawstring" called actin; creates a cell plate in plant cells, since their cell walls prohibit them from bending)

Question 18

What is a cell plate?

Accepted Answer

A structure in plant cells during cytokinesis that allows the plant cell to split

(constructed in the Golgi apparatus)

Question 19

What is the cleavage furrow?

Accepted Answer

A groove formed in animal cells between the two daughter cells, that pinches the two cells apart during cytokinesis

Question 20

What are kinetochores?

Accepted Answer

Protein complexes found on the centromere of each sister chromatid where the microtubules bind

Necessary for chromosome positioning and movement

Question 21

What is the G₁ checkpoint?

Accepted Answer

A checkpoint between the G₁ and S phases where the cell checks if it...

Size: is large enough

Nutrients: has enough nutrients

Molecular Signals: is receiving molecular signals (e.g., growth factors) from neighbors

DNA Integrity: has undamaged DNA

Question 22

What is the G₀ phase?

Accepted Answer

A resting state for cells where they are not actively dividing

(some cells stay here temporarily, while others stay here forever; cells who fail the G₁ checkpoint often move here until conditions improve)

Question 23

What is the G₂ checkpoint?

Accepted Answer

A checkpoint between the G₂ and M phases, where the cell checks if...

DNA integrity: any of the DNA is damaged

DNA replication: all of the DNA was copied during the S phase

Question 24

What happens if errors/damage is detected at the G₂ checkpoint?

Accepted Answer

The cell will pause and try to complete the DNA replication, or repair the replicated DNA

If the damage is irreparable the cell will die via apoptosis, which is important for preventing cancer

Question 25

What is the spindle checkpoint (M checkpoint)?

Accepted Answer

A checkpoint during the M phase where the cell checks if all the sister chromatids are correctly attached to the spindle microtubules

(anaphase is irreversible, so this is important)

Question 26

What is density-dependent inhibition?

Accepted Answer

A feedback mechanism that stops cells from growing when there are too many in a given area (they are too dense)

Cancer cells have often lost this, so they keep reproducing

Question 27

What is a cyclin?

Accepted Answer

Important cell-cycle regulators that drive the cell-cycle forwards by interacting with cyclin-dependent kinases (Cdks)

(as cyclins attach to Cdks, the Cdks are activated and directed to target the next phase (e.g., M cyclins send Cdks to M phase targets, making the nuclear membrane break down))

Question 28

What is negative feedback in hormones?

Accepted Answer

When a hormone attempts to inhibit more of that hormone from being produced

(when blood glucose is too high, the pancreas secretes insulin, which lowers the blood glucose level and stops the secretion of insulin)

Question 29

What is positive feedback in hormones?

Accepted Answer

When a hormone promotes more of its secretion

Question 30

What are microtubules?

Accepted Answer

Fundamental structures of the spindle apparatus that are essential for cell division

Question 31

What are motor proteins?

Accepted Answer

Proteins in kinetochores that move chromosomes during anaphase in mitosis

(in animal cells they can also be used to pinch the cell in two and generate the cleavage furrow)

Question 32

What are actin filaments?

Accepted Answer

Linear polymers that assemble at the cytokinesis site to generate the force to pinch the cell in two

Interact with myosin motor proteins

Question 33

How do cells communicate?

Accepted Answer

Generating, transmitting, receiving, and responding to chemical signals

Question 34

What is cell signaling?

Accepted Answer

Process of cells communication with each other in the body

(driven by the release of ligands which are detected by receptors)

Question 35

What is a ligand?

Accepted Answer

Any type of signalling molecules that cells use to communicate

(detected by receptors)

Question 36

What are receptors?

Accepted Answer

Proteins on cells that ligands bind to

(can be located on the cell membrane for hydrophilic ligands, or inside the cell for hydrophobic ligands that are small enough to cross the membrane)

Question 37

What is direct cell-to-cell signaling?

Accepted Answer

Type of cell signaling that involves direct physical contact between cells during communication

(signaling molecules flow through water-filled channels; gap junctions in animal cells and plasmodesmata in plant cells)

Question 38

What is paracrine signaling?

Accepted Answer

Type of signaling where cells are close to each other and release a short-lived signal that will induce changes in a nearby cell

(especially important during development; only works over short distances)

Question 39

What is synaptic signalling?

Accepted Answer

Unique example of paracrine signaling, where nerve cells transmit ligands called neurotransmitters over the synapse

Question 40

What is autocrine signaling?

Accepted Answer

Type of signaling where the cell signals to itself, releasing a ligand that binds to its own receptors

(in many cases a signal can be both autocrine and paracrine; important in cancer)

Question 41

What is endocrine signaling?

Accepted Answer

Type of cell signaling where distant cells communicate using hormones that are transmitted through the bloodstream

Question 42

What happens after a ligand binds to a receptor on a cell?

Accepted Answer

The cell relays the message through a series of reaction, creating a response from the cell

Question 43

What is a signal transduction pathway?

Accepted Answer

A chain of molecules that relay signals inside cells

Question 44

What are kinases?

Accepted Answer

Enzymes that catalyze the phosphorylation of proteins

(catalyze the addition of phosphate groups to proteins)

Question 45

What are phosphatases?

Accepted Answer

Enzymes that catalyze the dephosphorylation of proteins

(catalyze the removal of phosphate groups from proteins)

Question 46

Why are kinases and phosphatases important?

Accepted Answer

They can often be used to turn on/off proteins

(many proteins are activated when phosphorylated by kinases, and deactivated when dephosphorylated by phosphatases)

Question 47

Why is calcium important for cell signaling?

Accepted Answer

Some proteins have binding sites for calcium and change shape/function when calcium binds

(calcium is used in muscles to start muscle contraction; calcium=)

Unit 4: Cell Communication and Cell Cycle, AP Biology Flashcards