Unit 4 Cell Communication And Cell Cycle

Question 1

How is the process of distance communication different from the process of communicating during cell-cell contact?

Answer 1

Structural modifications of the cell membrane and cell wall allow cells to send chemical signals directly into adjacent cells.

Question 2

What is a signal transduction pathway?

(how does it cause a cellular response)

Answer 2

A signal transduction pathway is when the signal molecule a ligand binds to the receptor located on the cell surface or inside the cell that triggers events (a signal cascade) inside the cell, to invoke a response.

Question 3

Why do cells use signal transduction pathways? why is it so important?

Answer 3

to regulate cell communication in a wide variety of ways such as growth, secretion, and gene expression.

without it, it would make it impossible for cells to respond to the information given

Question 4

How does negative feedback maintain homeostasis?

Answer 4

Negative feedback maintains homeostasis by reducing the result of a reaction to bring the system back to a stable state. a hormone decreases to cause another hormone to decrease

ex: Blood sugar regulation (insulin lowers blood glucose when levels are high

once an infection is under control negative feedback is activated to lower your body temperature

Question 5

How does positive feedback affect homeostasis?

example?

Answer 5

Positive feedback maintains homeostasis by amplifying the result of a reaction to make it occur more quickly. a hormone increases to cause another hormone to increase

ex: glucagon raises glucose levels when they are to low

The hotter you get the more you sweat

The more growth hormone you have the taller you get

Question 6

What is the role of interphase?

What occurs during interphase?

Answer 6

allows newly divided cells the opportunity to grow, maintain normal cell function, and prepare for division.

cells grow, replicate DNA, and prepare for division.

Question 7

What is the role of mitosis?

What occurs during mitosis?

Answer 7

Mitosis plays a role in growth, tissue repair, and asexual reproduction.

During mitosis genetic information is transferred.

Question 8

What is the role of checkpoints in regulating the cell cycle?

Answer 8

Checkpoints help determine whether the cell is ready to progress through cell division.

Question 9

How are proteins are involved in checkpoints?

Answer 9

Proteins are used to activate or inhibit cell cycle activities.

Question 10

What happens if the cell cycle is disrupted?

Answer 10

Disruptions to the cell cycle may result in cancer and or programmed death (apoptosis)

Question 11

what are the three stages of signal transduction?

Answer 11

Reception: The signal molecule (ligand) binds to the receptor and changes the shape of the receptor protein in some way

transduction: The activated receptor triggers a chain of biochemical reactions in the cell. many different enzymes are involved. the entire reaction is called a signal cascade.

Response: cells respond to the messages and changes are made to the cell’s behaviour

Question 12

describe Autocrine signalling
is it short or long

usually involves helps with?

Answer 12

a cell signals to itself, releasing a ligand that binds to receptors on its own surface (or, depending on the type of signal, to receptors inside of the cell).
binds to itself
short

cytokines and neurotransmitters

helps regulate blood pressure, nervous system function, and reproduction

Question 13

describe cell to cell communication

Answer 13

it involves cells interacting with one another in two forms

communication by special channels between adjacent cells

cells bind to and communicate with each other because they have complements proteins on their surface

Question 14

Describe endocrine signalling
is it short or long

Answer 14

it’s a signal that is carried in the bloodstream to target cells (long distances) Mostly involves hormones or cytokinesis (small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells)

maintains homeostasis by producing hormones and secreting them into the blood stream

long

Question 15

Describe paracrine signalling
is it short or long

usually involves

helps with

Answer 15

allows cells to communicate with each other by releasing signalling molecules that bind to and activate surrounding cells. (signals move through diffusion)
short

cytokines and neurotransmitters

helps regulate blood pressure, nervous system function, and reproduction

Question 16

what’s a target cell

Answer 16

a specific cell that receives and responds to a message

Question 17

what happens in G1 phase when is their checkpoint and what do they check for?

Answer 17

the cell accomplishes most of its growth. they get bigger in size and make most of their organelles and proteins including RNA, centromere, and parts of the centrosomes.

checkpoint is at the end of G1 Phase

Check For…
Cell Size
Nutrients
Growth factor
DNA damage

Question 18

what happens in S phase when is their checkpoint and what do they check for?

Answer 18

occurs during interphase responsible for DNA replication.

Question 19

what happens in G2 phase when is their checkpoint and what do they check for?

Answer 19

The cell grows more and makes more organelles and proteins. begins to reorganize its contents in preparation for mitosis.

check for DNA damage and DNA replication

Question 20

How can cells communicate over varying of distances using different types of signalling

Answer 20

Depending on the distance cells use different types of signalling

Question 21

what is quorum sensing

Answer 21

a process of cell to cell communication that allow multiple bacteria to share information

Question 22

what is a cellular response

Answer 22

the way that cells respond to signals in their environment.

Question 23

Explain how a change in the structure of any signaling molecule affects the activity of the signaling pathway

Answer 23

by mutations and any mutation that alters the ligand/receptor can lead to incompatibility, the receptor won’t be able to properly shape change resulting in an inactive transduction pathway

Question 24

What is the function of a ligand? Give an example

Answer 24

Small molecules (signal molecules) that attach to the receptor site to start a signal transduction pathway

example steroid hormone

Question 25

How does Apoptosis help the overall health of a multicellular organism?

Answer 25

apoptosis is the process of programmed cell death. it’s used to eliminate unwanted cells such as
cancerous and virus-infected cells, and maintains balance in the body by a death signalling molecule being attached to the receptor.

Question 26

what happens in the M checkpoint?

Answer 26

checks if the spindle fibres are attached to the chromosomes

Question 27

What happens to a cell causing it to stop at G0?

Give an example of a cell arrested at G0.

Answer 27

The cell has received signals to stop dividing or they don’t meet the requirements of the checkpoints such as a lack of nutrients

Nerve cells remain at G0

Question 28

Describe what happens if the enzymes involved in the transduction pathway are denatured

Answer 28

Sometimes changes in environmental conditions such as temperature or PH around the cell causes denaturation of proteins and enzymes, which result in pathway disruptions. It eventually leads to cell death since the cells fail to respond to the change effectively.

Question 29

Describe what happens if an inhibitor is introduced at the receptor site

Answer 29

If an inhibitor is introduced to the receptor site then the all activates stop the signal is inhibited

Question 30

Describe the signal transduction pathway of a protein hormone and steroid hormone

Answer 30

see picture

Question 31

Describe the function of a cascade in a signal transduction pathway.

Answer 31

a signal cascade is a series of chemical reactions that occur within a cell when initiated by a stimulus and its function is to transmit biochemical information between the cell membrane and nucleus by amplifying the signal by activating the protein molecules and the secondary messengers in the cell

Question 32

Describe the function of a second messenger in the signal transduction pathway.

Answer 32

Second messengers are small molecules and ions that pass on information (signals) received by cell-surface receptors to effector proteins.