life at cellular level 1

Question 1

what is a cell

Answer 1

the living unit of all things

Question 2

why are cells so small

Answer 2

the bigger the cell, the smaller the SA:V, the smaller the exchange of gases

Question 3

difference between prokaryotic and eukaryotic

Answer 3

prokaryotic: 
1- no membrane bound organelles
2-DNA in loops- no nucleus-no membrane
3-bacteria cells
4-no mitochondria

Question 4

different types of stem cell

Answer 4

TOTIPOTENT; can differentiate into any cell. Difference with pluripotent is that it can give rise to embryo and placenta.
MULTIPOTENT-can differentiate into many different types of cell
PLURIPOTENT- Can differentiate into any cell

Question 5

what is the plasma membrane made up of?

Answer 5

phospholipid bilayer- hydrophobic tail and hydrophilic heads

proteins embedded into the layer which allow the membrane to carry out a series of functions.

Question 6

what functions does the cell-membrane have? (6)

Answer 6

1- transport
2-cell-adhesion
3-bonds to cytoskeleton and extracellular matrix
4-receptor
5-enzyme activity
6- cell to cell recognition

Question 7

Function of bonding to cytoskeleton and extracellular matrix?

Answer 7

helps maintain the structure of the cell

Question 8

Function of acting as a receptor?

Answer 8

Chemicals can bond to proteins embedded in the membrane. this might cause them to change shape and in turn initiate a chemical response inside the cell

Question 9

function of acting as an enzyme?

Answer 9

proteins embedded in membrane can catalyse an activity or a whole metabolic pathway.

Question 10

different types of transport?

Answer 10

• facilitated diffusion- Requires concentration gradient and carrier molecules
• diffusion-non-polar molecules which are lipophilic
• pinocytosis: Non -specific. Small molecules move into cell in many individual vesicles
• Receptor-mediated endocytosis
• Phagocytosis: Specific form of pinocytosis

Question 11

Cell death

Answer 11

Apoptosis- programmed cell death.

• Apoptosis and cell proliferation are what control cell development.
• Cell death can either be physiological(apoptosis) or pathological( response to an injury).
• Physiological- membrane bleb- few hours- no damage to adjacent cell
• Pathological- membranes rupture- days- inflammation- damage to adjacent cells-necrosis

Question 12

Cell signalling

Answer 12

• Paracrine- signalling cell releases local mediator to target cells
• Endocrine- hormone released into bloodstream-binds to receptors on target cells
• Autocrine
• Contact-depending: depends on cell adhesion
• Synapsing

Question 13

Cell organelles

Answer 13

Mitochondria:
-Outer membrane: contains porin
-Inside membranes: Cristae
-own DNA and ribosomes
Nucleus:
-Nucleoli-sites of rRNA synthesis.
-Nuclear envelope closely associated with RER
-DNA, nucleoproteins,RNA
ER
-rough-has ribosomes attached, works with Golgi in production of proteins and modification of proteins
-Smooth used for assembly of lipid compounds or breakdown of certain compounds e.g. drugs
Lysosomes;
-used for autophagy-destruction of cell-self material or engulfed particles
Cytoskeleton:
-made up of microfilaments, intermediate filaments and microtubules
-holds organelles in place, helps move them

Perixosome:

• contains catalase ( regulate hydrogen peroxide conc.)
• contains oxidase: involved in beta-oxidation