Cell Structure- 1

Front 1

What is a cell?

Back 1

A cell is the basic unit of life. It is enclosed by a cell surface membrane and contains genetic material (DNA) and cytoplasm containing organelles.

Front 2

What is an organelle?

Back 2

An organelle is a functionally and structurally distinct part of a cell.

Front 3

Give 2 examples of organelles.

Back 3

1. Ribosomes

2. Mitochondria

Front 4

What is a nucleus?

Back 4

A nucleus is a relatively large organelle found in eukaryotic cells but absent from prokaryotic cells; they contains the cell's DNA and therefore controls the activities of the cell ; it is surrounded by 2 membranes which together form the nuclear envelope.

Front 5

What is a eukaryote?

Back 5

A eukaryote is an organism whose cells contain a nucleus and other membrane-bound organelles.

Front 6

What is a prokaryote?

Back 6

A prokaryote is an organism whose cells does not contain a nucleus or other membrane- bound organelles.

Front 7

What is the source of radiation for the light microscope?

Back 7

The source of radiation for the light microscope is light.

Front 8

What is the source of radiation for the electron microscope?

Back 8

The source of radiation for the electron microscope are beams of electrons.

Front 9

Why is a coverslip (thin glass) used?

Back 9

It protects specimens from drying out and also prevents the objective lens from touching the specimen.

Front 10

What is a photomicrograph?

Back 10

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

Front 11

Why most of the cells should be stained to be seen under the light microscope?

Back 11

Many of the cell contents are colourless and transparent so they need to be stained with coloured dyes to be seen.

Front 12

Why plant cells containing chloroplasts need not be stained?

Back 12

Plants cells having chloroplasts have not been stained because the chloroplasts contain the green pigment chlorophyll and are easily visible without staining.

Front 13

Draw and label an animal cell as seen under the light microscope.

Back 13

M

N(3)

G

3C

Front 14

Draw and label a plant cell as seen under the light microscope.

Back 14

2M

N(3)

G

TV

PG

4C

Front 15

What is the function of the cell surface membrane?

Back 15

It is partially permeable and controls the exchange of materials between the cell and its environment.

Front 16

What is chromatin?

Back 16

Chromatin is 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.

Front 17

What is the function of DNA?

Back 17

DNA (deoxyribonucleic acid) is the molecule which contains the instructions (genes) that control the activities of the cell.

Front 18

What is a chromosome?

Back 18

In the nucleus of the cells of eukaryotes, a structure made of tightly coiled chromatin (DNA, proteins and RNA) visible during cell division.

Front 19

What is the nucleolus?

Back 19

The nucleolus is a small structure made of loops of DNA from several chromosomes. The nucleolus is usually visible as a densely stained body; its function is to manufacture ribosomes using the information in its own DNA.

Front 20

What is protoplasm?

Back 20

all the living material inside a cell is called protoplasm. (cytoplasm plus nucleus)

Front 21

What is the cytoplasm?

Back 21

the contents of a cell, excluding the nucleus.

Front 22

What is a mitochondrion?

Back 22

the organelle in eukaryotes in which aerobic respiration takes place

Front 23

Why do organelles often have one or two membranes?

Back 23

Organelles are often, but not always, surrounded by one or two membranes so that their activities can be separated from the surrounding cytoplasm.

Front 24

What is the function of the golgi apparatus?

Back 24

The Golgi apparatus collects and processes molecules within the cell, particularly proteins.

Front 25

What is a cell wall?

Back 25

A wall surrounding prokaryote, plant and fungal cells; the wall contains a strengthening material which protects the cell from mechanical damage, supports it and prevents it from bursting by osmosis if the cell is surrounded by a solution with a higher water potential

Front 26

Why is the cell wall rigid?

Back 26

The wall is relatively rigid because it contains fibres of cellulose, a polysaccharide which strengthens the wall.

Front 27

What are vacuoles?

Back 27

Vacuoles are sac-like structures which are surrounded by a single membrane.The plant vacuole is surrounded by a membrane, the tonoplast, which controls exchange between the vacuole and the cytoplasm. The fluid in the vacuole is a solution of pigments, enzymes, sugars and other organic compounds (including some waste products), mineral salts, oxygen and carbon dioxide

Front 28

What is the function of the large central vacuole?

Back 28

Vacuoles help to regulate the osmotic properties of cells.

Front 29

What is the chloroplast?

Back 29

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

Front 30

What are grana?

Back 30

stacks of membranes inside a chloroplast.are the parts of the chloroplast that contain chlorophyll, the green pigment which absorbs light during the process of photosynthesis.

stacks of membranes inside a chloroplast.are the parts of the chloroplast that contain chlorophyll, the green pigment which absorbs light during the process of photosynthesis.

Front 31

What is photosynthesis?

Back 31

Photosynthesis is the production of organic substances from inorganic ones, using energy from light

Front 32

State 2 common methods of seperating organelles.

Back 32

The 2 most common methods of seperating organelles are :

1. Homogenisation

2. Differential centrifugation

Front 33

State the conditions for homogenisation method. (3)

Back 33

The tissue is placed in :

1. Chilled (to inactivate enzyme and thus prevent self digestion )

2. Isotonic (no loss nor gain of water)

3. buffer solution (resist pH change)

to maintain integrity of organelles.

Front 34

In differential centrifugation; larger organelles are first filtered:

1. Nuclei

2. Mitochrondria and chloroplast

3. ER, golgi and other membrane fragments

4. ribosomes

Back 34

L

Front 35

What does cytosol consists of ?

Back 35

Cytosol consists mainly of water with dissolved substances such as enzymes for glycolysis (part of respiration) and other metabolic reactions together with sugars, salts, amino acids, nucleotides and everything else needed for the cell to function.

Front 36

Nucleus is the cell control centre.

Genetic materials stored as chromosomes in nucleus.

Genome : all genetic material in a cell

Back 36

L

Front 37

What is the function of the nuclear pore?

Back 37

Nuclear pores allows the passage between the nucleus and the cytoplasm.

Front 38

Describe nuclear pores.

Back 38

Nuclear pores are large holes containing proteins that control the exit of substances such as RNA and ribosomes from the nucleus.

Front 39

Nuclear membrane is a double membrane with nuclear pores.

Back 39

L

Front 40

What is chromatin?

Back 40

Chromatin is a DNA/protein complex containing the genes.

Front 41

What happens to the chromatin during cell division?

Back 41

During cell division, the chromatin becomes condensed into discrete observable chromosomes.

Front 42

What is the function of the nucleolus?

Back 42

The nucleolus synthesise ribosomes.

Front 43

What is the function of mitochondrion?

Back 43

Mitochondrion is the site where aerobic respiration takes place in all eukaryotic cells.

Front 44

Mitochondria is surrounded by a double membrane (an outer membrane and the inner membrane which folds into cristae)

Back 44

L

Front 45

Why the inner membrane of the mitochondria folds into cristae?

Back 45

The inner membrane of the mitochondria folds into cristae to increase the surface area.

Front 46

The matrix contains small cricular strands of DNA and the inner membrane contains ATP synthase , which are the site of ATP synthesis.

Back 46

L

Front 47

What is ER?

Back 47

ER is a network of membranes throughout the cytoplasm of the cell.

Front 48

What is the function of SER?

Back 48

Functions of SER:

1. Involved in synthesising and transporting materials, mainly lipids, needed by the cell

2. Helps in the detoxification of harmful substances in the cell.

Front 49

What is the function of RER?

Back 49

Ribosomes synthesise polypeptides, which are prossessed in the RER (by enzymatically modifying the polypeptide chain , or adding carbohydrates ) before being exported from the cell via the golgi body.

Front 50

What is the function of the golgi complex?

Back 50

The golgi complex is the organelle in the cell that is responsible for sorting and correctly shipping the proteins produced in the ER.

Front 51

Cisternae

Back 51

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Front 52

What are ribosomes composed of?

Back 52

Ribosomes are composed of rRNA and protein

Front 53

polysomes : groups of ribosomes

Back 53

.

Front 54

When the large and small subunits of RNA are docked with mRNA, they make proteins.

Back 54

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Front 55

What are vesicles?

Back 55

Vesicles help store and transport products produced by the cell.

Front 56

State 3 functions of lysosomes?

Back 56

Functions of lysosomes :

1. Digesting food or cellular invaders

2. Recycling cellular components

3. Cell suicide

Front 57

Lysosome is not found in plant cells

Back 57

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