Lecture 2: Cells

Question 1

What are the levels of organisation in an organism?

Answer 1

Organelles -> Cell -> Tissue -> Organ -> Organ system -> Organism

Question 2

What jobs do cells have and which cells perform these jobs?

Answer 2

1 - Detecting: sensory neurons, pancreatic beta cells.
2 - Signalling: neurons, endocrine cells
3- Digesting, absorbing or transporting: epithelial cells, red blood cells, exocrine cells
4- Fighting infection: leukocytes
5- Moving: Cardiac muscle, smooth muscle or skeletal muscle cells.
(DSDFM)

Question 3

What processes do cells undertake to do these jobs?

Answer 3

• Make things e.g. proteins, lipids, mRNA, DNA
• Break things down e.g. glucose, proteins, carbohydrates.
• Change membrane voltage e.g. especially neurons, muscle cells.
• Secrete/transport things e.g. neurotransmitters, glucose, digestive enzymes.
• Detect things e.g. light, sound, levels of different molecules

Question 4

Describe the parts of a cell

Answer 4

1- Cell membrane: surrounds cells and controls what enters and leaves through phospholipid bilayer and proteins.
2- Cytoplasm: The fluid inside the cell where chemical reactions happen. Contains watery cytosol which is made up of 70% water, ions, small molecules, amino acids, soluble proteins.
3 - Cytoskeleton: consists of filaments and tubules that crisscross the cytoplasm and help maintain cell shape.
4- Nucleus: contains most of cell DNA and acts as control center of the cell.
5- DNA: nucleic acid found in cells contains genetic instructions that cells need to make proteins.
6- Ribosomes: structures found in all cells that are site of protein synthesis.
7 - Endoplasmic reticulum: Organelle that helps make proteins and lipids and transports proteins in the cell.
8- Golgi apparatus: modifies, sorts and packages proteins for secretion out of the cell or use within the cell.
9- Lysosomes: use enzymes to break down molecules to be recycled.
10 - Mitochondria - Organelles that use energy stored in glucose to make ATP which is then used by cells for energy.

Question 5

What are some roles of proteins?

Answer 5

• Antibodies
• Contractile proteins e.g. myosin
• Strcutural proteins e.g. collegen
• Transport proteins
• Enzymes e.g. ATP synthetase
• Storage proteins e.g. ferritin
• Hormonal proteins e.g. insulin

Question 6

What is a protein?

Answer 6

Chain of amino acids in an order coded by the cell’s DNA

Question 7

Roles of ATP

Answer 7

1. Drive reactions e.g. protein synthesis
2. Muscle contraction and dilation
3. Move molecules against gradients
4. Transport proteins or organelles around the cell.
5. Move microtubules to allow cells to crawl or processes to move.
6. Produce heat to maintain body temperature.

Question 8

Describe the parts of a neuron

Answer 8

1. Dendrites
   2-Cell body/soma with nucleus
   3-Axon
   4- Axon hillhock
   5-Synapse
   6-Presynaptic terminal
   7- Myelin sheath
   8- Node of Ranvier
   9- Scwann cell

Question 9

Main types of neurons

Answer 9

• Sensory
• Relay
• Motor

Question 10

Are dendrites different for all neurons?

Answer 10

Some have spiny dendrites and some have smooth dendrites coming out of the dendrite spines. The axon can also be less or more branched depending on how many cells it communicates with/send signals to.These differences allow for different functions.

Question 11

What are other types of cells in the brain?

Answer 11

Glia cells e.g.
1. Astrocytes: star-shaped, control levels of neurotransmitters in synapses, move molecules around
2. Oligodendrocytes: produce myelin sheath to wrap around axons aiding neurotrasnmission
3. Microglia: brain’s resident immune cell, engulf any cell which is dead or damaged.