Cell biology

Question 1

what are the characteristic of all cells?

Answer 1

• Surrounding membrane
• Cytoplasm (cell contents in thick fluid)
• Organelles for cell function

Question 2

What is a prokaryotic cell?

Answer 2

• bacteria and archea. They are single celled organisms with a simple structure of just a single undivided interval area called a cytoplasm.
  They don’t have a membrane bound nucleus. They have a nucleoid where DNA concentration is. The organelles are not bound by membranes.

Question 3

What is a eukaryotic cell?

Answer 3

Multicellular organisms - complicated structure internally containing a membrane bound nucleus and a cytoplasm containing membrane bound components. They have many organelles & examples are skin cells. Fungi, protists, plant and animal cells.

Question 4

what is the nucleus?

Answer 4

The site of cellular DNA storage, replication & transcription. It contains chromosomes.
- DNA and histone proteins form chromatin. The Nucleolus is an area within it responsible for producing ribosomes. (composed of proteins and rna)

Question 5

What are ribosomes?

Answer 5

Composed of RNA & proteins. Carry out protein synthesis at 2 locations.

1. In cytosol - free ribosomes
2. Outside of the ER (bound)
   - They are not surrounded by a membrane

Question 6

what is the rough ER?

Answer 6

site of protein synthesis. Associated with the nucleus. Site of translation of proteins destined for membranes or secretion. It is covered in ribosomes.

Question 7

What is the Smooth ER?

Answer 7

Doesn’t contain any ribosomes. Involved in - carbohydrate metabolism, drug metabolism and ion movements.

Question 8

What is the endoplasmic reticulum?

Answer 8

Network of membranes enclosing flattened sacs called cisternae. It is connected to the outer membrane of the nucleus. This helps process molecules made by the cell and transports them to their specific destinations inside or outside cell. Transport vesicles bud off the ER and migrate to the GA.

Question 9

What is the Golgi apparatus?

Answer 9

Packing and shipping station. Main role is glycosylation and suffocation of proteins. Essentially modifying and packaging of proteins.

• Doesn’t contain any ribosomes
• 4 layers of thin, flat, enclosed vesicles laying near one side of nucleus. The substances are transported to the GA, then processed to form lysosomes etc.

Question 10

What are lysosomes?

Answer 10

Essentially destroy worm out organelles & break down waste materials in cells - important for immune function & microphages.

Question 11

What are the functions of lysosomes?

Answer 11

• Aid in cell renewal
• Break down old cell parts
• Digest invaders incl pathogens ingested by phagocytic cells.

Question 12

What are the components of lysosomes?

Answer 12

Contain digestive enzymes (catalase and oxidase) - for digestion of intra and extracellular molecules and debris.
- Surrounded by a lipid bilayer membrane.
pH between 4.5 - 5.5

Question 13

what Is the mitochondria?

Answer 13

Break down food molecules and site of energy production - produce ATP providing energy..

• They have own DNA
• bound by a double membrane

Question 14

What do mitochondria do?

Answer 14

Break down organic compounds (glucose, fatty acids) by aerobic respiration (oxygen requiring) to produce energy

Question 15

are mitochondria reproductive?

Answer 15

Yes and they can create their own enzymes

Question 16

What is the cytoskeleton? (& main elements)

Answer 16

Provide organisation & structure to cell - in cytoplasm. 
Main elements:
1. microtubules (made of tubulin)
2. Actin filaments
3. intermediate filaments

Question 17

What are the main functions of the cytoskeleton? (6)

Answer 17

• provide cell with shape and stability (but can be v dynamic and can change shape quickly)
• cell movement - dynamic
• Equal distribution of chromosomes into each new cell in mitosis
• Anchors cell to neighbouring cells and to protein network
• Microtubules serve as railways along which motor proteins pull transport vesicles
• Holds organelles in place

Question 18

What is a peroxisome?

Answer 18

Contains oxidative enzymes that produce hydrogen peroxide

Question 19

Cells have a large surface area to volume ratio. Eukaryotes are larger and thus larger diffusion distance and chemical reactions would occur slowly. What is in place to prevent this?

Answer 19

Compartmentalisation.

Question 20

What is compartmentalisation?

Answer 20

All cells possess an outer plasma membrane. Eukaryotic possess a system of internal membranes which set various closed compartment within the cell so all organelles are surrounded by membranes.

Question 21

What do membranes consist of?

Answer 21

Amphipathic phospholipids
Cholesterol
Proteins
etc

Question 22

what is in the membrane?

Answer 22

• Hydrophobic non polar tails

- Hydrophilic polar heads

Question 23

what do the hydrophilic phosphate heads do in the membrane?

Answer 23

They form both the inner and outer surface of the membranes - sandwiching fatty acid tails of the phospholipids to form a hydrophobic core inside membrane

Question 24

what is the cytoplasm?

Answer 24

dense viscous fluid containing organelles. It requires active transport processes in one cell.

Question 25

what are the components of the cytoplasm?

Answer 25

cytoplasm - microfilaments and fibres.
Cytosol (fluid)
Organelles (NO nucleus)
Storage substances

Question 26

GIVE 2 functions of actin filaments (cytoskeleton)

Answer 26

• determine cell shape

- Cell movement and muscle contraction

Question 27

give 2 functions of microtubules (cytoskeleton)

Answer 27

• essential in cell division

- internal transport system in cells