Cell Structure 1.1, 1.2 and 1.3

Question 1

Cell definition

Answer 1

The basic unit of all living organisms;
- surrounded by a cell surface membrane
- contains genetic material
- contains cytoplasm containing organelles.

Question 2

Organelle definition

Answer 2

A functionally and structurally distinct part of a cell, e.g: a ribosome or mitochondrion.

Question 3

Nucleus definition

Answer 3

A relatively large organelle found in eukaryotic cells but absent from prokaryotic cells; the nucleus contains the cell’s DNA and therefore controls the activities of the cell; it is surrounded by two membranes which together form the nuclear envelope.

Question 4

Eukaryote definition

Answer 4

An organism whose cells contain a nucleus and other membrane-bound organelles. (Animals, plants, fungi, and some other organisms)

Question 5

Prokaryote definition

Answer 5

An organism whose cells do not contain a nucleus or any other membrane-bound organelles. (Bacteria)

Question 6

What did eukaryotes (containing nuclei with DNA surrounded by two membranes) evolve from?

Answer 6

from prokaryotes (no nuclei and DNA free in cytoplasm) more than two billion years ago.

Question 7

What is the diameter of the smallest structure visible with a human eye?

Answer 7

50-100 μm in diameter.

Question 8

What are the sizes of the cells in your body?

Answer 8

5-40 μm.

Question 9

How large is a bacterial cell?

Answer 9

1 μm.

Question 10

How large is a ribosome?

Answer 10

25 nm.

Question 11

What fraction of a meter is a millimeter?

Answer 11

one thousandth = 0.001 = 1/1000 = 10^-3

Question 12

What fraction of a meter is a micrometer?

Answer 12

one millionth = 0.000 001 = 1/1000 000 = 10^–6

Question 13

What fraction of a meter is a nanometer?

Answer 13

one thousand millionth = 0.000 000 001 =
1/1000 000 000 = 10^–9

Question 14

Cell surface membrane definition

Answer 14

A very thin membrane (about 7 nm diameter) surrounding all cells; it is partially permeable and controls the exchange of materials between the cell and its environment.

Question 15

Chromatin definition

Answer 15

The material of which chromosomes are made, consisting of DNA, proteins and small amounts of RNA; visible as patches or fibres within the nucleus when stained. (Mass of coiled threads)

Question 16

Chromosome definition

Answer 16

In the nucleus of the cells of eukaryotes, a structure made of tightly coiled
chromatin (DNA, proteins and RNA) visible during cell division; the term ‘circular DNA’ is now also commonly used for the circular strand of DNA present in a prokaryotic cell.

Question 17

Nucleolus definition

Answer 17

A small structure, one or more of which is found inside the nucleus; the nucleolus is usually visible as a densely stained body; its function is to manufacture ribosomes using the information in its own DNA. (Loops of DNA from several chromosomes. 1-5 is common in mammals)

Question 18

Protoplasm definition

Answer 18

All the living material inside a cell (cytoplasm plus nucleus)

Question 19

Cytoplasm definition

Answer 19

The contents of a cell, excluding the nucleus. (Aqueous, jelly-like)

Question 20

Mitochondrion definition

Answer 20

The organelle in eukaryotes in which aerobic respiration takes place.

Question 21

Photomicrograph definition

Answer 21

A photograph of a specimen as seen with a light microscope.

Question 22

Why are stains used in light microscopes?

Answer 22

Because many of the cell contents are transparent.

Question 23

What cell content was discovered by use of stains containing silver and when?

Answer 23

Golgi apparatus/body/complex discovered by Camillo Golgi in 1898.

Question 24

What does the golgi apparatus do?

Answer 24

It collects and processes molecules within the cell, particularly proteins.

Question 25

Name 5 similarities between animal and plant cells

Answer 25

• cell surface membrane
• nucleus
• cytoplasm
• mitochondria
• golgi apparatus

Question 26

Name 4 differences between animal and plant cells

Answer 26

• centrioles
• cell walls and plasmodesmata
• vacuoles
• chloroplasts

Question 27

Why are plant cells more easily seen under a microscope than animal cells?

Answer 27

They have a cell wall.

Question 28

What links plant cells to other neighboring cells?

Answer 28

Fine strands of cytoplasm

Question 29

Cell wall definition

Answer 29

A fully-permeable wall surrounding prokaryote, plant and fungal cells; the wall contains a strengthening material which protects the cell from mechanical damage, supports it (shape) and prevents it from bursting by osmosis if the cell is surrounded by a solution higher than its water potential.

Question 30

Plasmodesma (Pl. plasmodesmata) definition

Answer 30

A pore-like structure found in plant cell walls; plasmodesmata of neighboring plant cells line up to form tube-like pores through the cell walls, allowing the controlled passage of materials from one cell to the other; the pores contain ER and are lined with the cell surface membrane.

Question 31

Vacuole definition

Answer 31

A sac-like organelle found in eukaryotic cells; a large, permanent central vacuole is a typical feature of plant cells, where it has a variety of functions including storage of biochemicals such as salts, sugars, and waste products; temporary vacuoles, such as phagocytic vacuoles (also known as phagocytic vesicles) may form in animal cells. Solution of pigments, enzymes, sugars and other organic compounds (incl. waste products) mineral salts, oxygen and carbon dioxide. In plants, vacuoles help to regulate osmotic properties of cells (flow of water inwards and outwards) and pigment of petals of flowers or red pigment of beetroot.

Question 32

Tonoplast definition

Answer 32

The partially permeable membrane that surrounds plant vacuoles and controls exchange between the vacuole and the cytoplasm.

Question 33

Chloroplast definition

Answer 33

An organelle, bounded by an envelope (two membranes) in which photosynthesis takes place in eukaryotes.

Question 34

Photosynthesis definition

Answer 34

The production of organic substances from inorganic ones, using energy from light.

Question 34

Grana (sing. granum) definition

Answer 34

Stack of membranes inside a chloroplast containing chlorophyll.