Biology Unit 1 (B2 Cell Specialisation)

What is a stem cell?

Unspecialised single cell that can differentiate into many types or replicate itself

What is the name of the process when a stem cell becomes a specialised cell?

Differentiation

Describe the function and structural features of a red blood cell

Function: transports oxygen and carbon dioxide around the body

Structural features:

• Biconcave shape:
  Increases surface area for faster oxygen diffusion and makes the cell flexible to move through narrow capillaries.

• No mitochondria or endoplasmic reticulum:
  Provides more space for haemoglobin to carry oxygen.

• Haemoglobin:
  Binds and carries oxygen to body cells for respiration.

• No nucleus:
  Frees up space for more haemoglobin and helps maintain the biconcave shape.

What is the function and structure of the neutrophil ( white blood cell)

Function:

• Part of the non-specific immune response.

• Engulfs and destroys pathogens (phagocytosis).

structural features:

• Multi-lobed nucleus: Makes the cell flexible so it can squeeze through capillary walls to reach infection sites.

• Many lysosomes: Contain enzymes that digest engulfed pathogens.

• Many ribosomes: Produce enzymes for the lysosomes.

• Flexible cell membrane: Helps the cell move between capillary cells and carry out phagocytosis.

Describe how pathogens are destroyed by neutrophils after they are ingested

• Pathogen enclosed in vesicle called phagosome

• lysosomes fuse with phagosome + form phagolysosome

• hydrolytic enzymes breakdown the pathogen

What is the function and structure of B and T Lymphocytes ( white blood cells)

Function:

• B-cells: Attack invaders outside cells by making antibodies.

• T-cells: Attack infected body cells directly.

Structural features:

• Large nucleus: Stores DNA; allows quick activation and cloning.

• Small cell size: Moves easily in blood to infection sites.

• Antigen receptors: Each receptor is specific to one antigen (specific immune response).

• Many mitochondria: Provide energy for antibody production (in B-cells).

What is the function and structural features of sperm cells

function: for reproduction

Structural features:

1. Mitochondria- provides ATP energy for movement through aerobic respiration.

2. Acrosome- membrane bound organelle that contains digestive enzymes (like acrosin). These enzymes help the sperm break through the egg’s outer layer (zona pellucida) so it can fuse with the egg.

3. Flagellum- Movement of sperm cell

4. Haploid Nucleus- contains 23 pairs of chromosomes and allows restoration of diploid number (46).

5. 5. Streamlined shape- reduces resistance when moving. 

What is the function and structural features of egg cells

Function: for reproduction

Structural features:

1. Mitochondria- provides ATP energy for movement of cortical granules inside of the cells through aerobic respiration.

2. Cortical Granules- membrane bound vesicles that contain enzymes which harden the zona pellucida

3. Cytoplasm- large to support cell division. It has lipid droplets that store energy for mitosis and contains organelles like mitochondria.

4. Haploid Nucleus- contains 23 pairs of chromosomes and allows restoration of diploid number (46).

5. Zona pellucida- hardens upon fertilisation to prevent polyspermy. 

6. Corona radiata- Outer protective layer of egg cell which protects and provides proteins for cells to grow.

What is the function and structural features of root hair cells

function: absorb water and minerals from the soil into the plant.

structural features:

1. Large Vacuole- keeps water levels in cytoplasm low, so more water enters from high to low concentration by osmosis.

2. Thin cell wall- shorter pathway so ions and water molecules enter faster

3. Root hair- provides a large SA to maximise the rate of osmosis

4. Mitochondria- provides energy for active transport of ions to the cell against their conc gradient via aerobic respiration. 

5. Plasmodesmata- connects cells to easily move water and minerals to plants core

6. Carrier and channel proteins- help ions and water molecules to enter the cell.  

What is the function and structural features of the mesophyll palisade cells

Function: carries out photosynthesis

structural features:

1. Large vacuole- takes up space, pushing the chloroplasts to the outside of the cell

2. Clear cell wall- allows light to penetrate the cell and be absorbed by chloroplasts inside

3. Cells are elongated and cylindrical- allows cells to be closely packed and increases SA for absorption of light

4. Many chloroplasts- contains chlorophyll in thylakoids, arranged in grana to maximise light absorption. 

5. cytoskeleton- moves chloroplasts to adjust to light conditions

6. Mitochondria- carries out aerobic respiration, providing ATP for photosynthesis.

7. Cell membrane-partially permeable, allowing small non-polar molecules like co2 to pass through.