Eukaryotic cells

Question 1

Definition

Answer 1

Eukaryotic cells are cells that contain a nucleus and organelles, and are enclosed by a plasma membrane and they also contain a membrane bound nucleus.

Question 2

All the organelles in the ultrastructure of animal cell

Answer 2

Cell surface membrane, Cytosol, Ribosome, Centriole, Rough/Smooth Endoplasmic Reticulum, Lysosome, Golgi apparatus, Nucleus, Nucleolus, Vesicles, Mitochondria

Question 3

Nucleus

Answer 3

• Largest organelle which protects majority of DNA and also produces necessary precursors for protein synthesis. DNA controls the metabolic activities of the cell.
• Contained within a double membrane called Nuclear Envelope which contains Nuclear Pores.
• DNA associates with proteins called histones to form a complex called chromatin. This coils and condenses to form structures known as chromosomes.

Question 4

Nucleolus

Answer 4

• Dense area within the nucleus and is responsible for producing ribosomes.
• Composed of proteins and RNA.

Question 5

Mitochondria

Answer 5

• They produce ATP which makes the energy stored in the bonds of complex organic molecules available to use.
• Number of mitochondria in the cell is a reflection of the amount of energy it uses.
• Mitochondria has double membrane- inner membrane is highly folded to make cristae and fluid interior is the matrix.

Question 6

Vesicles and Lysosomes

Answer 6

• Vesicles are membranous sacs that have storage and transport roles.
• Lysosomes are specialised forms of vesicles that contain Hydrolytic enzymes.
• They break down waste materials

Question 7

Flagella and Cilia

Answer 7

• Extensions that protrude from cells
• Flagella usually exist to enable cells mobility. In some cells they are used as a sensory organelle to detect chemical change in cell’s environment.
• Cilia can be mobile or stationary. Stationary are present on the surface of many cells and Mobile cilia beats in rhythmic manner, creating a current, causing fluids or objects next to the cell to move along.

Question 8

Cellulose cell wall

Answer 8

• Cellulose is a complex carbohydrate
• Freely permeable so substances can pass in and out if the cell
• Supports both the individual cell and the plant as a whole
• Defence mechanism as it protects plant cell against pathogens

Question 9

Vacuoles

Answer 9

• Membrane lined sacs in the cytoplasm containing cell sap
• Large permanent vacuoles maintain the structure as it forces the contents of the cell to push against cell wall
• Membrane of a vacuole is called Tonoplast which is selectively permeable

Question 10

Chloroplasts

Answer 10

• Responsible for photosynthesis and are found in cells of green plants
• Double membrane structure
• Fluid enclosed is called Stroma
• Has internal network of membranes called thylakoids -> several of these are called granum -> plural is grana and grana contain chlorophyll pigments