Higher Summary Notes - Cells

7/30/2019 Higher Summary Notes - Cells

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Hamilton Grammar School 1

Cells are the basic unit of all living things. There are a great variety

of cells whose structures are specialised to suit their functions.

These specialised cells are arranged into layers called tissues.There is great variation between tissues with some tissues

containing only one cell type and others having more than one.

SPECIALISED ANIMAL CELLS The following shows three

examples of specialised animal cells.

A red blood cell is biconcave in shape.

This provides a large surface area for

the uptake of oxygen. In addition

there is no nucleus. This allows it to

be filled with haemoglobin to pick up

oxygen.

RED BLOOD CELLS

These white blood cells defend

against illness. They have the ability

to change shape and engulf micro-

organisms in a process called

phagocytosis.

They contain lysosomes which contain

powerful digestive enzymes to digestmicrobes.

PHAGOCYTES

NERVE CELLS

Nerve cells have a long fibre

(insulated extension of cytoplasm).

This is able to transmit nerve impulses

long distances.


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There are many more and you should be able to learn four examples.

SPECIALISED PLANT CELLS There is great variety in plant cells as well.

Look at this picture of a leaf which has many specialised cell types within it.

How structure suits functionSpecialised FeaturesCell type How structure suits functionSpecialised FeaturesCell type

Smooth Muscle

Squamous Epithelium

( Cheek Lining )

Columnar Epithelium

( Cheek base )

Red Blood Cells

WBC

Phagocytes

Lymphocytes

Epithelial ( Goblet cells)

Nerve Cells

Epithelial ( Hair cells)

Spindle shaped andform sheets

Lets them contract andrelax to push food

Flat irregular shape Lets them form a loose

covering for protection

Tall wide and canmake squamous cells

Provides a foundation on whichsquamous cells built and protectslower layers

Small, biconcave discs = largesurface area. No nucleus andfilled with Haemoglobin

Lets lots of O2 diffuse inand be carried (Hb)

Cup shaped andproduce mucus

Mucus traps dust andgerms

Cilia on outermembrane

Cilia move mucus to backof the throat

Long insulated fibres Carry electrical impulses

Can change shape and havelysosomes with digestive enzymes

Engulf and destroymicrobes

Produce antibodies and havereceptors on membrane

Detect and inactivate

microbes


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They are long hollow tubes allowing

water to easily move up through the

plant.They are strengthened by rings or

spirals of lignin. This helps to support

the plant.

XYLEM VESSELS

PHLOEM VESSELS

There are 2 types of cells.

1. Cells belonging to a sieve tube.

The end walls of these cells are

perforated to allow cytoplasm to move

from one cell to another carryingfood. These perforated end walls are

called sieve plates.

2. Companion cells

The companion cells contain a nucleus

which controls the movement of

soluble carbohydrates (sugars) down

the sieve tube.

GUARD CELLS

Guard cells found mainly on the

bottom surface of a leaf and are

sausage shaped with a thick inner cell

wall facing stoma pores

The guard cells control gas exchange

and water loss by changing shape andopening or closing the pores.


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There are many more plant cell types and you should be able to learn at

least four of the following examples.

UNICELLULAR ORGANISMS

Some living things are made up of only one specialised cell. These uni-

cellular organisms contain many specialised structures which allow them to

carry out all the processes required for life.

AMOEBA

How structure suits functionSpecialised FeaturesCell type How structure suits functionSpecialised FeaturesCell type

Xylem vessels

Tracheids

Phloem

Spongy Mesophyll

Guard Cells

Palisade Mesophyll

Hollow tubes whichare lignified and dead

Allows water transportand gives stem support

Hollow spindleshaped lignified cells

Gives stem extra support

Allows cytoplasm to movecarrying food

Contains large nucleusAllows control of itselfand sieve cell

Round shape andchloroplasts

Produces air spaces for gasdiffusion and can dosecondary photosynthesis

Columnar and packedwith chloroplasts

Produces a tightly packedlayer of photosyntheticcells

Sausage shaped withthicker inner wall Allows stomata to open andclose for gas exchange

Companion cells

Epidermal cells

Root Hair Cells

Perforated end wallsand no nucleus

Sieve cells

Box or irregular shapethat fit tightly together

Produce a strongprotective coat

Long extension intothe soil

Produces a large surfacearea for water absorption

ContractileVacuole

Pseudopod

Food beingengulfed

Food vacuole

Cytoplasm

Pseudopodia

CellMembrane Nucleus

Specialised features include:-

Pseudopodia these surround the food

source.

Food vacuole this contains digestive

enzymes which breakdown the food

Contractile vacuole controls waterbalance


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PARAMECIUM

EUGLENA

Cilia

FoodVacuoles

Oral

GrooveCellMouth

MicronucleusMacronucleus

ContractileVacuole

Paramecium, like amoeba, is a single celled animal and contains many

specialised structures.

Macronucleus Contains genetic information which controls daily cell reactions

Micronucleus Contains genetic information which is passed on throughreproduction.

Ciliated Groove Small hairs sweep food down into food vacuole

Food Vacuole Digests food and allows end products to diffuse to all parts of cell

Macronucleus Contains genetic information which controls daily cell reactions

Anal Pore Expels digested material from cell

Euglena show plant and animal features.

Cell membrane

Food store / reserve

Light detector

Eyespot

FlagellumChloroplast

Second Flagellum

Contractile Vacuole

Nucleus

Euglena is a plant and has

many features which aid

photosynthesis :-

Chloroplasts Trap light

energy for photosynthesis.

Eye Spot Detect light

source

Flagellum help Euglena move

towards the light


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CELL ULTRASTRUCTURE

All cells contain many specialised organelles which can only be seen with the

aid of high magnification electron microscopes. During this unit you will

learn about most of them in more detail so dont freak out when you see the

following diagrams and descriptions as they will make more sense by the

time you have finished this unit.

ANIMAL CELLS

The cell is like a factory with the organelles being similar to specialised

machines which provide energy, build the proteins needed for life and

transport them about the cell. The code for all proteins is found in the

nucleus in the form of DNA.

nucloeolus

nucleus

nuclear

membrane

mitochondrion

Smooth

Endoplasmic

Reticulum

Rough Endoplasmic Reticulum

Golgi body

Secretory vesicles

lysosomes

centrioles

Plasma

membrane


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PLANT CELLS

Nucleus Contains DNA packed into chromosomes

Cytoplasm This is the main site of chemical activity and has many

specialized organelles

Mitochondria main site of respiration and energy release Ribosomes bodies involved in protein synthesis Endoplasmic reticulum transport of proteins (rough) and lipids

(smooth)

Golgi apparatus involved in packaging proteins for secretion Lysosomes contain powerful digestive enzymes and break down

worn out organelles or food engulfed by the cell.

Cell membrane Controls the movement of molecules into and out of

the cell

Channels

Cellulose Cell Wall

Large Vacuole

Chloroplasts

Cell walls with cellulose give plant cells their shape and addmechanical strength

Channels - connections linking plant cells Large permanent vacuole fluid filled organelle

Chloroplasts

Site of photosynthetic light and dark reactions

Plant cells contain all

the organelles presentin animal cells and even

have a few more which

are unique to plants.

Higher Summary Notes - Cells

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