Biology 2.1 Cell Structure

Question 1

What is cell theory?

Answer 1

It is universally accepted theory where
- cells are the structural and function units of living things.
- all living things are made of cells, or the product of cells.
- every cell arises from a pre-existing cell.
cells contain hereditary material.

Question 2

what is the size of a prokaryotic cell?

Answer 2

Small (1-10)

Question 3

what is the size of an eukaryotic cell?

Answer 3

Large (10-100)

Question 4

is there a presence of nucleus in prokaryotes

Answer 4

no

Question 5

is there a presence of nucleus in eukaryotes?

Answer 5

yes

Question 6

internal Organisation in prokaryotic and eukaryotic cells.

Answer 6

Prokaryotic cell: Simple
Eukaryotic cell: complex

Question 7

Membrane bound organelles in prokaryotes and eukaryotes

Answer 7

Prokaryotes have none. Eukaryotes have many such as mitochondria, golgi body, endoplasmic reticulum, lysosomes etc.

Question 8

DNA in prokaryotes and eukaryotes

Answer 8

Prokaryotes have circular chromosomes whereas eukaryotes have linear chromosomes.

Question 9

what kind of cell division is used in prokaryotes and eukaryotes

Answer 9

prokaryotes use binary fission. Eukaryotes use mitosis and meiosis.

Question 10

what organelles does a plant cell have?

Answer 10

only plant cells have chloroplasts and central vacuoles

Question 11

what organelles does animal cells have?

Answer 11

only in animals cells where there are many small vacuoles.

Question 12

what does the nucleus do?

Answer 12

contains DNA and is enclosed by a double membrane called a nuclear envelope. controls amount and type of protiens available inside the cell. nuclear pores are present in the nuclear envelope that allows mRNA to move into the cytoplasm.

Question 13

What does the nucleolus do?

Answer 13

• An area within the nucleus where ribosomal RNA (rRNA) is transcribed to produce ribosomal subunits.
• Known as the site of ribosomal biogenesis.
• Plays a vital role in making proteins.

Question 14

What does Mitochondria do?

Answer 14

• The site of aerobic respiration and the production of ATP (used for energy).
• Known as the ‘powerhouse of the cell’.
• Has two membranes: the outer membrane and the inner membrane (highly folded to form cristae and increase surface area for efficiency).

Question 15

What does chloroplast do?

Answer 15

• PLANT CELLS ONLY (and other photosynthetic autotrophs).
• Contain a system of flattened sacs (thylakoids) that contain the pigment
  chlorophyll (used to trap light energy for photosynthesis).
• Thylakoids are arranged in stacks called grana lamella, surrounded by
  stroma (a matrix ‘fluid’).

Question 16

what does the vacuoles do?

Answer 16

• A membrane-bound, fluid-filled space that usually contains water and dissolved minerals.
• They maintain water and salt balance.
• PLANT CELLS: usually contain one large, central vacuole.
• ANIMAL AND FUNGAL* CELLS: usually contain multiple, small vacuoles

Question 17

What does the golgi body do?

Answer 17

• A complex of vesicles (membrane bags) and folded membranes.
• Important in packaging and secretion of chemicals (a post office).
• Produces secretory enzymes (eg: digestive enzymes in pancreas) and forms lysosomes.
• Transports and stores lipids (fats).

Question 18

What does the endoplasmic reticulum do?

Answer 18

• A system of membrane layers that extend from the nuclear membrane to the
  cell membrane.
• Transports materials to different parts of the cell.
• Rough ER: has ribosomes on its surface and is involved in protein synthesis.
• Smooth ER: does not have ribosomes and
  is involved in producing lipids and steroids.

Question 19

What does the ribosome do?

Answer 19

• Play a key role in protein production, specifically in translation.
• Found in both prokaryotes and eukaryotes.
• Made up of two subunits: a small subunit and a large subunit.
• Can be free-floating in the cyotplasm or attached to the rough endoplasmic reticulum in eukaryotes.

Question 20

What does lysosomes do?

Answer 20

• A membrane-bound organelle that contains digestive enzymes.
• Functions to break down unwanted macromolecules.
• Involved in digesting food and breaking down a cell when it dies.

Question 21

what is the cytoskeleton made of?

Answer 21

The cytoskeleton is made of protein fibres of different sizes.

Question 22

what are the functions of the cytoskeleton?

Answer 22

• Maintains cell shape.
• Strengthens the cell.
• Anchors organelles in place.
• Assists with mitosis (the spindle is a microtubule structure)
• Cell movement (flagella and cilia are composed of microtubules)

Question 23

What is the cell membrane made of?

Answer 23

The cell membrane is made of a phospholipid bilayer that encloses the contents of a cell.

Question 24

How does the structure of the cell membrane help?

Answer 24

It is thin to allow for rapid exchange of materials and a semi-permeable barrier, which regulates what enters and exits the cell.