CELL STRUCTURE AND

CELL ORGANISATION

CHAPTER 2

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Cellular components of

animal & plant cells

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Plant Cells

Animals Cells

Cell wall

Plasma

membrane

Vacuole

Chloroplast

Nucleolus

Nucleus

Ribosomes

Vesicles

Golgi

Apparatus

Rough Endoplasmic

Reticulum

Plasma

membrane

Smooth Endoplasmic

Reticulum

Mitochondrion

LysosomeVacuole

Centriole

Cytoplasm

Cellular components

Organelles

Vacuoles

Nucleus

Ribosomes

Endoplasmic reticulum

Golgi apparatus

Lysosomes

Centrioles (animal cell only)

Chloroplast (plant cell only)

Non-organelles

Plasma membrane

Cytoplasm

Cell wall (plant cells only)

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Functions

Nucleolus

Nucleus

Controls all the cell activities

Separates the genetic material

from cytoplasm

Has many pores (nuclear pores) in

the nuclear membrane for

materials to enter & exit the nucleus

Nucleolus is involved in the synthesis

of ribosome & ribonucleic acid (RNA)

Ribosomes

Are either attached to the ER

or occur freely in the

cytoplasm

Are small ‘protein factories’

for protein synthesize

Synthesizes &

transports proteins

made by ribosomes

Present in large

amounts in cell that

makes protein

E.g. in gut cells that

manufacture

digestive enzymes

Rough Endoplasmic

Reticulum

Receives proteins

from Rough ER,

modifies & combines

the proteins with

carbohydrates to

form glyco-protein

Transport & stores

lipids

Golgi Appratus

Does not have

ribosomes

Synthesizes &

transport lipids

Present in large

amounts in cells that

make lipids & steroids

E.g. cell of liver &

testes

Smooth Endoplasmic Reticulum

Forms the cell’s

powerhouse

Produce adenosine

triphosphate (ATP),

which is the energy

source for the cell

Mitochondrion

Supports & protects

the cell organelles

provides a medium

for all cellular

metabolic reactions

Cytoplasm

medium to produce

energy, to manufacture

materials & to store

minerals

Break down macromolecules such as

proteins, lipids, nucleic acids, polysaccharides

as well as worn-out organelles

Lysosome

Transport undigested

material to the cell

membrane for

removal

Are found only in

animals cells

Involved in cell

division (mitosis &

meiosis)

Centriole

The outer covering of

the cell

separates the cell

from its environment

and allows materials

to enter and leave

the cell

Plasma membrane

Comparing &

contrasting the structure

of animal and plant cells

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Animal cells Plant cell

Similarities

Both animal and plant cells have plasma membrane, cytoplasm, nucleus,

endoplasmic reticulum, Golgi apparatus, ribosomes and mitochondria

Differences

Not fixed SHAPE Fixed

Absent CELL WALL Present

Absent CHLOROPLAST Present

If present, are small & scattered throughout the cell

VACUOLE Has one or a few large vacuole(s) filled with cell sap

Present LYSOSOME Normally absent

Present CENTRIOLE Absent

Carbohydrates are stored in the form of glycogen granules

FOOD STRORAGE Carbohydrates are stored in the form of starch grains

The Density of Certain

Organelles in Relation to

Functions of Specific

Cells

What are organelles?

“little organs”

Are tiny structures inside a cell that

perform specific functions for the

cell

20

What are organelles?

“3 main functions of organelles:

a. Carry out their specialized functions:

E.g. Mitochondria; FUNCTION?

b. Acts as containers to separate parts of the cell from other

parts

E.g. lysosomes

c. Sites for chemical reaction

E.g. Chloroplast

Relationship between the Density &

Functions of certain Organelles

Density of an organelles :

total number of that particular organelles within

a cell

depends on the function of the cell

to make sure that the cell can perform its specialized functions well

Relationship between the Density

& Functions of certain Organelles

E.g.

Cell that specialize in producing enzyme generally have more ER &

ribosomes to _____________& mitochondria to

_____________________for its activities

The density of mitochondria in

active cells

Depends on:

a) The activity level of an organism

The more active an organism is, the higher its average density of mitochondria

b) The specific function of a particular cell

Cell of active tissues & organs have higher mitochondria densities

The density of mitochondria in

active cells

Active cells that have high mitochondria densities:

Sperm cells

flight muscle cells

meristemic cells

liver cells

kidney cells

The density of Chloroplast in the

Palisade Mesophyll Cells of

Leaves

Palisade mesophyll

of a leaf is : the main photosynthesis

tissue

Packed with chloroplast

to trap sunlight needed to

synthesize sugar during

photosynthesis

Are arranged in a vertical

position to optimise

sunlight trapping

Type of cells Function Density of certain

organelles

Sperm cells To swim towards either one of the Fallopian tubes to fertilise the ovum

Mitochondria – are sites of cellular respiration in which energy in the form of ATP is generated through oxidation of food substances such as glucose

Flight muscle cells

insects and birds

Contraction and relaxation of muscles

provide movement & locomotion

Mitochondria

Cells in the meristem Divided actively to produce new cells for growth

Mitochondria

Palisade mesophyll cells

Carry out photosynthesis Chloroplast – contain chlorophyll which trap light energy for photosynthesis

Goblet cells in the respiratory tract

Secrete mucus Golgi apparatus

Liver cells Detoxification of drugs Smooth endoplasmic reticulum

Pancreatic cells, cells of salivary glands, stomach cells, cells of intestine

Produce enzyme Rough endoplasmic reticulumand golgi apparatus