Cells and Organelles

Question 1

What are the different components of the plasma membrane

Answer 1

Phospholipids, carbohydrates, proteins and cholesterol

Question 2

Function of cholesterol in the plasma membrane

Answer 2

Maintain fluidity and stability of membrane

Question 3

Function of carbohydrates in the plasma membrane

Answer 3

Allow cell signalling and recognition

Question 4

Describe the structure of the nuclear membrane

Answer 4

Bilayer
Outer layer is continuous with endoplasmic reticulum
Inner layer is continuous with nuclear lamins

Nuclear pores control entry/exit of the nucleus

Question 5

What is the function of nuclear lamins and what part of the cytoskeleton do they fall under

Answer 5

Maintain structure of the nucleus
Involved in chromatin organisation

Lamins are intermediate filaments

Question 6

Function of peroxisomes + some examples

Answer 6

Involved in oxidative reactions eg. lipid oxidation, bile biosynthesis

Question 7

Function of lysosome

Answer 7

Breakdown of old, unwanted and foreign particles

Question 8

Describe the structure of the mitochondria

Answer 8

Two membranes with an intermembrane space

Inner membrane creates protrusions called cisternae

Inner space is called matrix

Contains ribosomes involved in protein synthesis

Question 9

How does mitochondria participate in apoptosis

Answer 9

Apoptosis signals cause release of Bcl12 which causes the release of Cytochrome C, which is usually in mitochondria, into cytoplasm where it activates caspase cascade

Question 10

Functions of the cytoskeleton

Answer 10

Maintaining cell shape and structure
Allow for organelle movement
Allow for cell attachment to other cells and ECM
Helps cell resist mechanical stress
Support fragile plasma membrane

Question 11

What are the three types of cytoskeleton

Answer 11

Microfilaments

Intermediate filaments

Microtubules

Question 12

What protein makes up the microfilament + its motor protein

Answer 12

Actin and motor protein myosin

Question 13

Key functions of microfilaments

Answer 13

Forming extracellular structures eg. microvilli and stereocilia

Support membrane allowing for cell contraction or change in shape

Create membrane extensions eg. lamellipodia and filopodia allowing cell motility

Form contractile ring in cytokinesis

Question 14

What are some of the proteins found in intermediate filaments

Answer 14

Keratin
Desmin
Vimentin
Lamins

Question 15

What protein makes up microtubule + its motor proteins

Answer 15

Tubulin

Motor proteins dynein and kinesin

Question 16

Function of intermediate filaments

Answer 16

Provide structural integrity to the cell

Question 17

Function of microtubules

Answer 17

Movement of cellular cargo
Cell motility eg. motile cilia and flagella
Movement of chromosomes in mitosis/meiosis

Question 18

What cells feature lots of microtubules

Answer 18

Sperm cells

Cilia cells

Question 19

What specific motor protein makes up flagella

Answer 19

Dynein

Question 20

What are lipid rafts in the plasma membrane

Answer 20

Areas where cholesterol and certain proteins are highly concentrated and act as signalling centres

Question 21

Definition of amphipathic

Answer 21

When a molecule has both a hydrophobic and hydrophilic component

Question 22

Three primary functions of caspase cascade

Answer 22

Destroy nuclear lamins

Activate DNases

Destroy cell adhesion proteins

Question 23

What cells contain lots of microfilaments

Answer 23

Stereocilia and microvilli

Question 24

What cellular structures contain lots of microfilaments

Answer 24

Lamellipodia and filopodia

Question 25

What are the three main cellular junctions

Answer 25

Tight, GAP and anchoring

Question 26

Four anchoring junctions, where they bind and what part of the cytoskeleton to

Answer 26

Adhesions - Bind to actin - Cell to Cell Desmosomes - Bind to intermediate filaments - Cell to Cell Focal adhesions - Bind to actin - Cell to ECM Hemidesmosomes - Bind to intermediate filaments - Cell to ECM

Question 27

Where are hemidesmosomes particularly found

Answer 27

In the dermal-epidermal junction connecting epithelial cells to the basement membrane

Question 28

Functions of tight junctions

Answer 28

Prevent movement of particles from cells to adjacent cells Maintain cell polarity

Question 29

Functions of GAP junctions

Answer 29

Allow passage of small ions from one cell to another

Question 30

What protein do tight cells bind to

Answer 30

Actin

Question 31

What happens in Tay Sachs disease + defective component

Answer 31

Failure to degrade lipids, leading to lipid accumulation and neurodegeneration Defective lysosome

Question 32

What two conditions arise from defective GAP junctions

Answer 32

Inherited deafness Vohwinkel's Syndrome

Question 33

Signs of vohwinkel syndrome

Answer 33

Crusty skin

Question 34

Cause of epidermolysis bullosa simplex + signs

Answer 34

Defective hemidesmosomes leading to blistering and red skin

Question 35

What mutation causes vohwinkel syndrome

Answer 35

Connexin-26

Question 36

What proteins make up GAP junctions

Answer 36

Connexin

Question 37

What proteins make up tight junctions

Answer 37

Claudins

Question 38

What proteins make up adhesion and desmosome junctions

Answer 38

Cadherins

Question 39

What proteins make up focal adhesion and hemidesmosomes

Answer 39

Integrins

Question 40

What causes Kartagener syndrome + Common signs

Answer 40

Dynein mutation leads to dysfunctional cilia and flagella Male infertility and recurring respiration infections

Question 41

Function of smooth ER

Answer 41

Calcium storage Lipid synthesis