Chapter 3 - Cell Structure

Question 1

Cell

Answer 1

The smallest biological entity that still retains the characteristics of life

Question 2

Two main types of cells

Answer 2

1) Prokaryotic Cells

2) Eukaryotic Cells

Question 3

What are Prokaryotic Cells?

Answer 3

• Small cells that don’t have a nucleus or membrane-enclosed organelles
• Eg. Bacteria

Question 4

What are eukaryotic cells?

Answer 4

• Large cells that have a nucleus and cell organelles, which are both enclosed by membranes
• eg. Animal cells

Question 5

Where are the DNA of eukaryotic cells located?

Answer 5

In the chromosomes

Question 6

Cell ultrastructure

Answer 6

The structure of a cell as seen with an electron microscope

Question 7

Cell membrane

Answer 7

• a.k.a. Plasma membrane

- a very thin boundary around the cell

Question 8

3 functions of a cell membrane

Answer 8

1) Control what enters and leaves the cell
2) Gives support/ holds in contents of the cell
3) Recognise the molecules that touch them

Question 9

Cell membrane is composed of

Answer 9

Phospholipids and proteins

Question 10

List the 6 labels in a cell membrane diagram

Answer 10

1) Pore
2) Proteins
3) Phospholipid
4) Phosphate Head
5) Lipid Tail
6) Phospholipid Bilayer

Question 11

Selectively permeable

Answer 11

Allows the free passage of some molecules and prevents the passage of others

Question 12

Cytoplasm

Answer 12

The watery solution that fills the cell, which is 90% H2O

Question 13

Functions of the cytoplasm

Answer 13

1) Acts as a storage are for nutrients
2) To support and separate the organelles
3) Medium in which most metabolic reactions occur

Question 14

Cytosol

Answer 14

Th liquid part of the cytoplasm (cytoplasm without organelles)

Question 15

Nucleus

Answer 15

• A spherical structure surrounded by the nuclear membrane with contains DNA and the nucleolus
• Largest organelle in the cell

Question 16

DNA in the nucleus

Answer 16

In the form of chromosomes or chromatin

Question 17

Nucleolus

Answer 17

An area in the nucleus where ribosomes are made

Question 18

Functions of the nucleus

Answer 18

1) Directs the activity of the cell
2) DNS replication and nuclear division
3) Controls the formation of mRNA (transcription)

Question 19

Nuclear membrane

Answer 19

• A double membrane which contains numerous pores

Question 20

Functions of the nuclear membrane

Answer 20

1) To retain nuclear contents

2) Has pores to allow materials in and out of the nucleus

Question 21

Give the labels four labels of the nucleus

Answer 21

1) Nucleolus
2) Nuclear pore
3) Chromatin
4) Double Nuclear Membrane

Question 22

Ribosomes

Answer 22

-Small organelle shaped like a burger bun which is made of RNA and protein

Question 23

Function of the ribosome

Answer 23

-Site of protein synthesis, a process called translation

Question 24

Mitochondrion

Answer 24

• A rod shaped organelle which has its own DNA and ribosomes which is surrounded by a double membrane
• Has inner membrane containing unfolding a which increase the surface area

Question 25

Function of the mitochondrion

Answer 25

1) Powerhouse of the cell

2) Site of respiration, (release of energy from food)

Question 26

Cell Wall

Answer 26

• Made from cellulose(a carbohydrate)

- Fully permeable ie. Cannot control what leaves and enters the cell)

Question 27

Two functions of the cell wall

Answer 27

1) Provides support and mechanical straight to the cell and the whole plant
2) Stops cell membrane bursting when the cell is full of water

Question 28

Large Vacuole

Answer 28

• Membrane filled with fluid called cell sap

- Fills the centre of the cell pushes content to the edge of the cell

Question 29

Two functions of the large vacuole

Answer 29

1) Stores sugar and salt dissolved in the water

2) Stores excretory products

Question 30

Chloroplast

Answer 30

An organelles with internal membrane stacks which contain the green pigment called chlorophyll , surrounded by a double membrane and has its own DNA and ribosomes

Question 31

Chloroplast Function

Answer 31

Trap sunlight during photosynthesis which allows plants to make their own food in the form of glucose

Question 32

Simple microscopes

Answer 32

Microscopes composed of a single lens just like a magnifying glass

Question 33

Compound microscopes

Answer 33

Microscope with two lenses

Question 34

Electron microscope

Answer 34

Electrons pass through a vacuum so not to be deflected by air molecules
(Provide a much higher magnification but the samples are placed in a vacuum and therefore cannot be living)

Question 35

T.E.M.

Answer 35

Transmission Electron Microscope
-Sends a beam of electrons through a thin section of the specimen allowing the internal structure to be viewed in great detail

Question 36

S.E.M.

Answer 36

Scanning Electron Microscope

-Uses beams of electrons to provide a surface view of the specimen

Question 37

Magnification formula

Answer 37

Magnification= objective x eyepiece

Question 38

Stage

Answer 38

The stage holds the slide which contains the specimen to be viewed

Question 39

Diaphragm (microscope)

Answer 39

The diaphragm controls the amount of light reaching the specimen

Question 40

Fine focus

Answer 40

The fine focus sharpens the image under high and low power. It moves the stage by small amounts

Question 41

Coarse focus

Answer 41

The coarse focus focuses the image under low power

Question 42

Objective lens

Answer 42

A lens attached to the nosepiece which magnifies the specimen

Question 43

Eyepiece lens

Answer 43

The eye piece lens magnifies the image, usually 10 times