12424403 pure bio chp 2 cells

7/30/2019 12424403 Pure Bio Chp 2 Cells

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Bio Chp 2: Cells 1

cells

Chapter 2

Pure biology


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Bio Chp 2: Cells 2

Learning outcomes

State the definition of cells.

State the role of cells in an organism. Identify organelles of typical plant and animal cells from diagrams,

photomicrographs, and as seen under a microscope:

chloroplasts, cell membrane, cell wall, cytoplasm, cell vacuoles, nucleus

Identify the following membrane systems and organelles from

diagrams and electron micrographs: endoplasmic reticulum, mitochondria, Golgi body, ribosomes

State the functions of the membrane systems and organellesidentified above.

State the relationship between cell function and cell structure for the

following: absorption root hair cells

conduction and support xylem vessels

transport of oxygen red blood cells

Differentiate cell, tissue, organ and organ system.


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Bio Chp 2: Cells 3

What are cells?

Definition

Cells are the simplest units that have all thecharacteristics of life.


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Bio Chp 2: Cells 4

What are cells?

In an organism, the cell...

takes in raw materials, and

processes the materials to make new molecules.

The molecules can be used by the cell itself, or

when transported to other parts of the body.


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Bio Chp 2: Cells 5

Studying Cells...

Cells have to be examined under

a microscope.

2 types are commonly used:

Light microscope: up to 1 000x

Electron microscope: up to 200 000x

Pictures from microscopes are

known as micrographs.

Light micrographs: colour images

Electron micrographs: black-and-white, can be artificially colourised.

light microscope

electron

microscope


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Bio Chp 2: Cells 6

The Protoplasm

Cells in the body may not look the same, but they

have similar parts.

Living material in the cell is known as protoplasm. It

is made up of:

water (about 70%)

proteins

carbohydrates

fats

3 parts:Cell surface membrane

Cytoplasm

Nucleus


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Cell Surface Membrane

Also known as the plasma

membrane.

Surrounds the cytoplasm of

the cell.

Partially permeableallows only some substances

to cross it

controls substances entering

or leaving the cell.

Note:

Cell membranes can also be found within the cell in the form of

organelles. Cell membranes are made up of phospholipid layers (chp 4).



Cytoplasm

Occurs between the cell

membrane and nucleus.

Most cell activities occur here.

Contains enzymes and

organelles.Organelles carry out various

functions in the cell.

Can be in sol, liquid, gel, or

semi-solid state. Most organelles are not

visible under light microscope.



Nucleus

Consists of:

nucleoplasm: small mass of

denser protoplasm

surrounded by a nuclear

envelope

Functions:

controls cell activities (growth,

repair)

essential for cell division


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Bio Chp 2: Cells 10

Cell Wall

Found only in plant cells.

Encloses the entire plant cell, surrounding the cell

surface membrane.


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Bio Chp 2: Cells 11

Cell Wall

Non-living

Made up of cellulose

Fully permeable

2 functions:

protects cell from injurygives plant cells a fixed shape


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Bio Chp 2: Cells 12

parts of The Nucleus

The parts of the nucleus can be seen using an

electron microscope.

4 components:

nucleolus

chromatin

nucleoplasm

nuclear envelope


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Bio Chp 2: Cells 13

Nuclear envelope and nucleolus

The nuclear envelope separates the contents ofthe nucleus from the rest of the cytoplasm.

The nucleolus is a dense spot in the nucleus. It

plays a part in making proteins in a cell.

nucleolus

chromatin

nucleoplasm

nuclear envelope


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Bio Chp 2: Cells 14

chromatin

Long, thread-like structures found in the nucleus.

Controls the activities of the cell, e.g. cell division.

Each chromatin is made up of proteins and

deoxyribonucleic acid (DNA).

During cell division, chromatin threads condense to

become chromosomes.

nucleolus

chromatin

nucleoplasm

nuclear envelope


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Bio Chp 2: Cells 15

Chromosome


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Bio Chp 2: Cells 16

Parts of the Cytoplasm

The cytoplasm contains:

organellesmitochondria

vacuoles

chloroplasts (plant cells only)centrioles (animal cells only)

membrane systems rough / smooth endoplasmic

reticulumGolgi apparatus


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Bio Chp 2: Cells 17

Rough Endoplasmic Reticulum


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Bio Chp 2: Cells 18


Has ribosomes attached to its outer surface.

Has a rough surface when viewed under the microscope.

Outer surface is continuous with the nuclear

envelope.

Tubes are generally flat. Transports proteins made by ribosomes to the Golgi

apparatus.


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Bio Chp 2: Cells 19


Ribosomes

Small and round

Some attached to RER

Make proteins to be transported out of the cell

Some lie freely in the cytoplasmMake proteins to be used in the cell cytoplasm.


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Bio Chp 2: Cells 20

Smooth Endoplasmic Reticulum

Does not have ribosomes

attached to its membrane.

More tubular in shape

Connected to the RER.

Function:Synthesis of fats and steroids

(e.g. sex hormones in

mammals)

Detoxification: convertsharmful substances into

harmless materials.


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Bio Chp 2: Cells 21

Golgi Apparatus

Also known as Golgi body

Disc-shaped

Consists of a stack of

flattened spaces surrounded

by membranes.

Vesicles fuse with one side

of the Golgi apparatus and

pinch off from the opposite

side.


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Bio Chp 2: Cells 22

Golgi Apparatus

Functions:

Store and modify

substances made by the

ER

Packages thesubstances in vesicles

for secretion out of the

cell.


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Bio Chp 2: Cells 23

The

ER-Golgi Link


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Bio Chp 2: Cells 24

Mitochondria

Singular: mitochondrion

Small, sausage-shaped organelles

Has a double membrane.

Aerobic respiration occurs here.Food substances are oxidised to release energy.

Energy is used by the cell for growth and reproduction.

inner membrane

outer membrane


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Bio Chp 2: Cells 25

Chloroplasts

Found in plant cells only.

Contain .

Important organelle for .


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Bio Chp 2: Cells 26

Vacuoles

A fluid-filled space

enclosed by a

membrane.

Stores substances

within the cell.

In animal cells:

Many small vacuoles

Contain water and food

substances

Usually exist temporarily

vacuole


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Bio Chp 2: Cells 27

Vacuoles

In plant cells:

Large central vacuole

Contains cell sap (dissolved

sugars, mineral salts and

amino acids)

Enclosed by a largemembrane known as the

tonoplast.

tonoplast


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Bio Chp 2: Cells 28

The Animal Cell


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Bio Chp 2: Cells 29

The Plant Cell


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Bio Chp 2: Cells 30

Specialized cells, tissues, organs and

systems

Living organisms grow through cell division,producing new cells.

New cells may differentiate to enable them to carry

out specific functions.

Differentiation:

A process by which a cell becomes specialized for a

specific function.


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Bio Chp 2: Cells 31

Specialized Cells

Specialized cells have specific structures to enable it

to carry out its specific function.


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Bio Chp 2: Cells 32

Red Blood Cellbiconcave

shape

Increases surface area to volume ratio

of the cell, allowing oxygen to diffuseinto and out of the cell at a faster rate.

Circular biconcave shape

Allows the red blood cell to carry more

haemoglobin.

No nucleus

Haemoglobin transports oxygen from

the lungs to all parts of the body.

Contains haemoglobin (red

pigment)

functionstructure


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Bio Chp 2: Cells 33

Root Hair Cell

nucleus

root hair

(long and narrow)


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Bio Chp 2: Cells 34

Root Hair Cell

Increases surface area to volume ratio of

the cell. The absorption of water and

mineral salts from the soil can be moreefficient.

Long and narrow

functionstructure


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Bio Chp 2: Cells 35

Xylem Vessel

lignified walls


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Bio Chp 2: Cells 36

Xylem Vessel

Lignin strengthens walls and prevents

vessels from collapsing. A bundle ofxylem vessels is known as wood, which

provides mechanical support to the plant.

Walls are lined with lignin

Enables water to move easily through the

lumen (central space)

No cross-walls or

protoplasm

Conduct water and mineral salts from the

roots to the stems and leaves.

Long, hollow tubes formed

out of xylem cells joined end

to end

functionstructure


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Bio Chp 2: Cells 37

Cells in a

Multicellular Organism

Multicellular organisms are organisms that are made

up of many cells. Cells do not work alone; they work together with

other cells.

many cells living thing


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Bio Chp 2: Cells 38

Cells group together to form TISSUE

Tissue is a group of cells working together toperform a specific function.

Cells of the same type form simple tissue.

Different types of cells group together to form

complex tissue.


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Bio Chp 2: Cells 39

Simple Tissue in Animals

Epithelial tissue (epithelium)

A sheet of cells which covers internal and external

surfaces of the body.

The sheet of cells covering the external surface of

the body is known as the epidermis.


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Bio Chp 2: Cells 40

Simple Tissue in Animals

Muscle tissue

A collection of muscle cells which contract and relax

to help the body move.


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Bio Chp 2: Cells 41

Simple Tissue in Plants

The leaves and stems of plants have covering

tissues also known as the epidermis.

The cells here are called epidermal cells.

stomata


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Bio Chp 2: Cells 42

Complex Tissues in Animals

Connective tissue Found inside an organ or between organs

Consists of a few types of cells

The whole tissue has one function: to connect

different parts of an organ or organs together.


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Bio Chp 2: Cells 43

Complex Tissues in Animals

Other complex tissues:

Nervous tissue

Glandular tissue

Bone tissue


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Bio Chp 2: Cells 44

Complex Tissues in Plants

Vascular tissue:

Made up of xylem and phloem tissues

Xylem tissue

Phloem tissue

Vascular tissue


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Bio Chp 2: Cells 45

Tissues work together to form ORGANS

Different tissues may be united to form an organ.

The different tissues work together to perform a

specific function.


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Bio Chp 2: Cells 46

Organs in Animals

The stomach consists of 4 kinds of tissues:

Glandular tissue: secretes digestive juices

Muscular tissue: causes stomach contractions, for

mixing food

Connective tissue: connects the other tissuestogether

Nervous tissue: coordinates the actions of the

stomach

*Refer to TB Pg 103!


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Bio Chp 2: Cells 47

Organs in Animals

Sense organs

The skin is the largest organ in the body.

Other sense organs include the eyes, ears, nose

and mouth.


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Bio Chp 2: Cells 48

Organs in Plants

The leaf:

A photosynthetic organ

Contains 4 tissues:

Palisade tissue

Mesophyll tissue

Xylem tissue Phloem tissue

*Refer to TB Pg 129!

Other plant organs: roots, stems, flowers.

Organs work together to form ORGAN


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Bio Chp 2: Cells 49

Organs work together to form ORGAN

SYSTEMS

Organ systems are made up of several organsworking together for a common purpose.

Examples of organ systems in animals:

Digestive system (Chp 6)

Respiratory system (Chp 8)Nervous system (Chp 13)


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Various systems work together to make up

the ORGANISM!

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