Animals cells

Question 1

What is metabolism in cells?

Answer 1

Synthesis and breaking down of molecules

Question 2

Why is the nucleus in a nuclear envelope?

Answer 2

Double membrane; keep it away from damage in the cytoplasm; contains nuclear pores - allow molecules to move in & out of the nucleus

Question 3

Why does DNA associate with the protein ‘Histones’?

Answer 3

To form chromatin; it coils and condenses to form chromosomes

Question 4

What is the nucleolus composed of?

Answer 4

Proteins and RNA. RNA is used to produce ribosomal RNA (rRNA)

Question 5

Where is energy stored?

Answer 5

Bonds of complex molecules (ATP)

Question 6

Structure of Mitochondria?

Answer 6

Double membrane; inner one folded (cristae) & huid interior = matrix; membrane contains enzymes for aerobic respiration; has a little bit of own DNA (mtDNA)

Question 7

Structure of Vesicle?

Answer 7

Single membrane with fluid inside

Question 8

What enzymes do lysosomes have?

Answer 8

Hydrolytic enzymes (for immune system)

Question 9

Microtubules structure and function?

Answer 9

Globular tubulin proteins polymerise to form tubes; acts as tracks for organelle movement; Makes spindle fibres

Question 10

Microfilaments structure and function?

Answer 10

Formed from protein actin; cell movement and cell contraction during cytokinesis

Question 11

What are intermediate fibres used for?

Answer 11

Give mechanical strength and help maintain the cells integrity

Question 12

What forms centrosomes?

Answer 12

Two centrioles (no centrioles in flowering plants and fungi)

Question 13

What is the flagella used for?

Answer 13

Cell mobility; in some cells used for sensing

Question 14

Cilia function and structure?

Answer 14

On the surface of cells (sensory); Beat in a rhythmic manner-current (trachea). Each ciliam has 2 central microtubules surrounded by 9 pairs of microtubules (9 + 2 arrangement)

Question 15

What is the endoplasmic reticulum?

Answer 15

Network of membranes enclosing flattened sacs (cisternae) connected to the outer membrane of the nucleus

Question 16

Function of Smooth ER and Rough ER?

Answer 16

Smooth ER= Lipid and carbohydrate synthesis and storage

Rough ER= Ribosomes bound to surface and responsible for protein synthesis and transport

Question 17

Golgi apparatus structure?

Answer 17

Compact structure of cisternae, no ribosomes. Packaging into vesicles or lysosomes

Question 18

What is the process of protein synthesis?

Answer 18

(1) mRNA is transported from the nucleus to the rough ER
(2) Proteins are synthesised on ribosomes on rough ER
(3) Proteins are packaged into transport vesicles
(4) Vesicle moves to golgi via cytoskeleton
(5) Vesicle fuses with cis face of the golgi and proteins enter
(6) Proteins are modified before leaving golgi from trans face
(7) Secretory vesicles carry proteins to cell surface membrane and fuse with it, releasing their contents (exocytosis)