Cell Structure

Question 1

Function and structure of Ribosome

Answer 1

Structure: Smaller subunit is where mRNA is read and decoded, larger subunit is where amino acids are added

Function: Reads mRNA to synthesise proteins

Question 2

Function and structure of Mitochondria

Answer 2

Function: Synthesises ATP during the final stage of aerobic respiration

Structure: Outer membrane provides protection, inner membrane folds to form structures called cristae. Also contains circular DNA and enzymes for respiration

Question 3

Function and structure of Lysosome

Answer 3

Function: Assists in phagocytosis and destruction of useless components of a cell

Structure: Phospholipid bilayer containing digestion enzymes

Question 4

Function and structure of Golgi apparatus

Answer 4

Function: To alter the sugar chains attached to proteins

Structure: Stack of curved, thin and fluid filled membranes

Question 5

Function and structure of Cell wall

Answer 5

Function: Provides structure and support while also preventing the cell from bursting when filled with water and can transport water. Can also be a carbohydrate store by changing amount of cellulose it holds.

Structure: Wall is made of cellulose, contains small channels to connect neighbouring cell cytoplasm’s, rigid structure

Question 6

Function and structure of Nucleus

Answer 6

Function:
Nucleus-Controls cell activity and stores DNA
Nucleolus-Creates ribosomes
Nuclear envelope-Separates chromatin from other components
Nuclear pores-Allows transport of large substances through nucleus

Structure: Nucleolus at the centre which surrounded by chromatin and nucleoplasm. All inside the nuclear envelope that has nuclear pores all over. Forms a ball shape

Question 7

Function and structure of Chloroplast

Answer 7

Function: Creates energy for the cell through photosynthesis

Structure: Contains stroma which is a liquid to add volume and protect internal structures, contains Lamellae which link Grana, Grana is involved in photosynthesis, made of two membranes.

Question 8

Function and structure of Rough Endoplasmic Reticulum

Answer 8

Function: Produces proteins, breaks or builds covalent bonds on proteins post-translation, folds and sorts proteins

Structure: Covered in lots of ribosomes to make proteins, made of flattened double membranes, provides a large SA for chemical reaction and is connected to the nuclear envelope

Question 9

Function and structure of Smooth Endoplasmic Reticulum

Answer 9

Function: Site of production for lipids, cholesterol and steroids and also stores them

Structure: Folds of flattened double membrane that is loose in the cytoplasm and contains enzymes

Question 10

Function and structure of Cell surface membrane

Answer 10

Function: Controls the flow of substances in and out of the cell

Structure: Made of a phospholipid bilayer that includes proteins and cholesterol that can have carbohydrate chains attached

Question 11

Function and structure of Centrioles

Answer 11

Function: Produce mitotic spindle for cell division, involved in the formation of cilia and undulipodia

Structure: Hollow cylinders that have sets of three microtubules going around the outside

Question 12

Function and structure of Cytoskeleton

Answer 12

Function: Maintains shape and stability of cell, allows movement of substances within the cell and movement of cell itself, forms track that motor proteins work along, forms spindle fibres for cell division

Structure: Made of actin filaments and microtubules, contains cytoskeletal motor proteins

Question 13

Function and structure of Chromatin

Answer 13

Function: Condenses to form chromosomes during cell division

Structure: Made of stored DNA and histone proteins

Question 14

Function and structure of Vacuole

Answer 14

Function: Prevents the cell from bursting when lots of water is absorbed, stores substances like water, sugar, enzymes and pigments

Structure: Only exists in plant cells, surrounded by a membrane called the tonoplast, filled with cell sap, becomes turgid when filled

Question 15

Function and characteristics of Cilia

Answer 15

Characteristics: Short, hair like substances located all over the cell, contains 9 pairs of microtubules around the outside and 1 pair in the middle(known as the 9+2 formation), only found in eukaryotes

Function: Allow the cell to move around or past other substances and objects around the cell

Question 16

Function and characteristics of Undulipodia

Answer 16

Characteristics: Long, strand like substances usually singular and is connected to the cell membrane, only found in eukaryotes

Function: Allows the cell to move and propels liquids over the cell

Question 17

3 points about a Eukaryotic cell

Answer 17

1) 10-100μm in size
2) DNA is always membrane-bound in the nucleus and separate form the cytoplasm
3) Are: animal, plant, fungal cells

Question 18

3 points about Prokaryotic cell

Answer 18

1) 1-5μm in size(on average)
2) DNA is suspended freely in cytoplasm in form of DNA loop/nucleoid
3) Often extremophiles due to simple cell structure

Question 19

Protein synthesis and secretion cycle

Question 20

State 3 ways in which prokaryotic and eukaryotic organisms differ in cell structure (3 marks)

Answer 20

Prokaryotic:
DNA is stored in a loose loop in the cytoplasm
Does not contain a nucleus
Cell organelles freely float in the cell

Eukaryotic:
DNA is stored in strands in the nucleus
Contains a nucleus to control cell activities
Cell organelles are bound by a membrane

Question 21

What are 2 processes inside cells that rely on the cytoskeleton for movement

Answer 21

Photosynthesis

Phagocytosis

Question 22

Which component of a cell contains RNA molecules and is found within another organelle

Answer 22

Nucleolus

Question 23

Why can live cells not be viewed under a scanning electron microscope

Answer 23

The specimen must be viewed in a vacuum, so that electrons are not deflected