2.4/5 Cell Ultrastucture

Question 1

microfilaments

Answer 1

Made from protein actin

Responsible for movement of the cell and cytoplasm during cytokinesis

Question 2

Microtubules

Answer 2

Globular protein tubulin
Polymerise to form tubes that determine the shape of the cell
Act as tracks for organelles

Question 3

Intermediate fibres

Answer 3

Gives strength to cells and helps maintain integrity

Question 4

Name all the structures in the nucleus

Answer 4

Double nuclear envelope
Nuclear pores
Nucleolus
Chromatin

Question 5

Double nuclear envelope

Answer 5

Double membrane which compartmentalises the nucleus and prevents damage.
Protects DNA

Question 6

Nuclear pores

Answer 6

Allows molecules to enter and leave the cell

Question 7

Nucleolus

Answer 7

Site of ribosome production composed of RNA and proteins

Question 8

Chromatin

Answer 8

Contains the genetic code which controls the activity of the cell

Question 9

Function of the nucleus

Answer 9

Controls all activity of the cell
Where genetic code is stored and replicated
Nucleus is attached to rough ER so the mRNA can easily get to ribosomes

Question 10

Rough endoplasmic reticulum

Answer 10

Stacks of membrane bound fluid sacs called cisternae
Covered ribosomes
Interconnected system of flattered sacs
Site of protein synthesis

Question 11

Smooth endoplasmic reticulum

Answer 11

No ribosomes
System of interconnected tubes
responsible for carbohydrate and lipids synthesis
Flattered sacs called cisterne

Question 12

Ribosomes

Answer 12

2 subunit organelle 
Made from RNA and protein 
No membrane 
Where protein is made 
They assemble amino acids into protein chains using mRNA

Question 13

Mitochondria

Answer 13

Oval shaped . Double membrane
Inner membrane is folded - cristae ( increase surface area)
Soulution inside is called matrix - contains enzymes for respiration
Mitochondrial DNA - small amounts of DNA enable mitochondrion to reproduce and create enzymes

Question 14

Golgi apparatus

Answer 14

Stacks of flattened , membrane bound sacs - cisterne
Allows internal transport
Receives protein from the RER
Modifies and processes molecules , by adding other molecules such as lipids and carbohydrates and packages them into vesicles
Makes lysosomes , lipid synthesis

Question 15

Lysosomes

Answer 15

Spherical sacs surrounded by a single membrane
Contain powerful hydrolytic digestive enzymes- lysozymes
Role is to break down worn out components of other cells or digest invading cells

Question 16

Centrioles

Answer 16

Component of the cytoskeleton composed of many microtubules
Small hollow cylinders in pairs next to the nucleus in animal cells
Each centriole contain a ring of 9 microtubules ( 9+2 formation) - arrangement allows movement
Makes a copy of itself during cell division and the helps to form the spindle in cell division
Hair like extensions that protrude form some animal cells
Sensory function.

Question 17

Flagella

Answer 17

Similar to cilia but longer
Protrude from the cell curvaceous and are surrounded by plasma membrane
Like cilia they have a 9+2 arrangement
Whip like , enables a cells mobility. Microtubules contract to make the flagellum move

Question 18

Chloroplasts

Answer 18

Double membrane which encloses the Stroma
Stroma contains : starch grains, lipid stores , DNA , RNA , ribosomes
Series of membrane bound flattened sacs called thylakoids in the Stroma . Thylakoids stacked together are called grana. Grana are linked by lamellae. The grana contain chlorophyll

Question 19

Cell plasma membrane

Answer 19

Membrane found on the surface of animal cells and inside the cell wall of plant and prokaryotic cells
A phospholipid bilayer
Composed of proteins and lipids
Regulates the movement of stub stances into and out of the cell
Contains receptor molecules which allows it to respond to chemicals like hormones

Question 20

Large permanent vacuole

Answer 20

Single membrane
Sores cell sap
Selectively permeable barrier
Supports herbaceous plants by making cells turgid
Sugars and amino acids act as a temporary food store

Question 21

Cellulose cell wall

Answer 21

Cell wall is fully permeable to substances
Thin layer called middle lamella marks the boundary between adjacent cell wall
Gives mechanical strength and support
Contents of the cell can push against the cell wall

Question 22

importance of the cytoskeleton

Answer 22

Aids transport vesicles within cells due to microtubules 
Provides scaffolding for cell 
Movement of chromosomes 
Cytokines 
Movement of cilia or flagella

Question 23

Structure in animal cells that are not present in plants

Answer 23

Centriole + lysosomes

Question 24

How do the organelles work together to release protein molecules from the cell

Answer 24

mRNA transcribes the genetic code for the proteins from the nucleus
RER or ribosomes is the site of protein synthesis where the genetic code is translated
Protein is packaged into a vehicle and transported to the Golgi
Protein is then modified
Vesicles travels to the cell surface membrane where it fuses by exocytosis out of the cell

Question 25

Functions and flagella and cilia

Answer 25

Enables movement of cells by moving liquid past the cell

E.g sperm

Question 26

Name a stage during the secretion of a protein that requires energy

Answer 26

Transport of vesicles to the cell surface membrane

Exocytosis