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CELL STRUCTURE AND CELL ORGANISATION

 All

living things are made up of basic units called cells  The living component of a cell is protoplasm. It consist of cytoplasm and the nucleus

nucleus

cytoplasm

 The

nucleus content is known as nucleoplasm  Nucleus is surrounded by cytoplasm

 The

protoplasm is surrounded by plasma membrane  Cytoplasm contains a variety of tiny structure called organelles

 Organelles

are cellular component that perform specific function within the cell

 Some

of the cellular components can only be seen under an electron microscope

Animal cell

Plant cell

The cellular components of animals and plant cells  There

are many similarities and differences between animal and plant cells

 Both

cells have the following cellular components: a) Nucleus b) Cytoplasm c) Plasma membrane

 Plant

cells have cell walls, chloroplast and large vacuoles  Animal cells do not have cell wall and chloroplasts

 Vacuoles

inside the animals cell are usually small  Only a few types of cells have vacuoles

Plasma membrane  A thin flexible layer  Composed of phospholipids and proteins  Semi-permeable – acts as a selective barrier

 Function

:  Separates the contents of a cell from its external environment

 Regulates

the movement of substances entering and leaving the cell  Allows the exchange of nutrients, respiratory gases and waste product

Cytoplasm  Consist of a jelly like medium in which cell’s organelles are suspended  Contains organic and inorganic substances

 Functions

:  As a medium where biochemical reactions and most living processes occur within the cell

 Provides

the organelles with substances from the external environment

Cell wall  Composed of cellulose  Permeable to all fluids because it has tiny pores

 Functions

:  Maintain the shape of the cells

 Provide

mechanical strength and to plant cells  Protect plant cells from rupturing

Vacuoles/vesicles  Fluid filled sacs enclosed by semipermeable membrane called tonoplast  The fluid is called cell sap

 Functions

:  Store chemicals such as organic acids, sugars, amino acid, mineral salts, oxygen, carbon dioxide, waste substances, pigments and metabolic by product

 Contributes

to plant elongation by absorbing water and causing cells to expand

Nucleus  Consist of three main components : a. Nuclear envelope b. Chromatin – carries genetic material c. Nucleolus – darker and dense region

Functions :  contains DNA which determines the characteristics of a cell and its metabolic functions

 DNA

carried information to direct and controls the activities of the cells eg. Protein synthesis

Mitochondria  Contain respiratory enzymes involved in cellular respiration

 Functions

:  The sites of cellular respiration

 Cellular

respiration releases energy through the oxidation of glucose

 Energy

is generated in the form of ATP (Adenosine triphosphate)

Ribosomes  Consist of ribonucleic acid (RNA) and protein

 Functions

: - the sites of protein synthesis

Endoplasmic reticulum  Two forms of ER : - rough ER – covered with ribosomes - smooth ER – does not have ribosomes

 Functions

:  Rough ER – transport protein made by the ribosomes throughout the cells

 Smooth 

ER – synthesises lipids (phospholipids and steroid) - carries out detoxification of drugs and metabolic byproducts

Golgi apparatus  Functions : - processing, packaging and transport centre of carbohydrates, proteins and glycoproteins

Lysosomes  Contain hydrolyctic enzymes

 Functions

:  Digestive compartments in a cell  hydrolyctic enzymes digest or break down complex organic molecules such as proteins, nucleic acids, lipid

 Break

down unwanted structures – old organelles, old cells

Centrioles  Composed of a complex arrangement of microtubules  Not present in plant cells

 Functions

: - form spindle fibre during cell divisions in animal cells

- synthesis cilia and flagella which help in the movement of some unicellular organisms

Chloroplast  Contain green pigment – chlorophyll

 Functions

: - chlorophyll captures the energy of sunlight and convert light into chemical energy during photosynthesis

Exercise 1. Name the three main cellular components of living cells 2. Which cellular component of a cell a. is made up of cellulose b. contains genetic information c. controls the movements of substances into and out of the cells

3. Name the organelles that are found in large numbers in a. muscle cells b. mesophyll palisade cells

 Find

out the similarities and differences between animal cells and plant cells

The density of organelles in specific cells  The

density or abundance of certain organelles in a cell is related to the specific functions of the cell

mitochondria Sperm cells Muscle cells Meristem cells

Require energy for movement

Chloroplast

Mesophyll palisade

Absorb sunlight

Rough endoplasmic reticulum Golgi apparatus

Pancreatic cells Salivary glands cell

Synthesize and secrete enzymes

Smooth endoplasmic reticulum

Intestinal epithelium

Secretes digestive enzymes Interstitial cells (testis, Synthesise and secrete steroids, adrenal glands) hormones Carbohydrates Liver cells metabolism

Golgi apparatus

Goblet cells (respiratory tract, intestinal epithelium) Root cap cells

Secrete mucus Secete slimy lubricants to helps movement of roots

Living processes in unicellular organisms -Can feed, respire, excrete, move, respond to stimuli, reproduce, grow

 Eg.

Protozoa, Amoeba sp., Paramecium sp.

Amoeba  Habitat

– freshwater lakes, pond, damp soil

 Characteristics:

- has plasma membrane - use pseudopodia for movement

 Locomotion

: - using cytoplasmic projection – extending pseudopodia and anchoring tips to the ground

 Feeding

: - phagocytosis –engulf food - approach food particles

- pseudopodia extend out and enclose food particles

- food particles are packaged in food vacuole -lysozyme digest food particles using hydrolyctic enzyme

- nutrients diffuse into cytoplasm and assimilated

 Respiration

– diffusion through plasma membrane

O2

CO2

 Excretion

: - CO2, ammonia – diffusion - water – contractile vacuole contract to expel water

 Response

to stimuli : - retreating from light, acidic solutions

 Reproduction

: - binary fusion – abundant of food - forming spores – food is scarce

Paramecium sp.  Habitat

– freshwater pond  Characteristics : - covered with cilia

 Locomotion

: - rhythmic beating of cilia - move forward and rotating spiraling along its axis

 Feeding

: - microscopic organisms - cilia – sweeps water and suspended food into cytostome

- food vacuole are formed - digested by hydrolyctic enzyme

- nutrients – dissolve and diffuse into cytoplasm - undigested contents – released through anal pore

 Respiration

: - gas exchange – diffusion

 Excretion

: - waste product – expelled through diffusion - osmoregulation is help by contractile vacuoles

 Response

to stimuli : - sensitive to – chemicals, oxygen, carbon dioxide, pH, light, , temperature

 Reproduction

-

: asexually, sexually macronucleus – control metabolism, asexual reproduction micronucleus – sexual reproduction

 Favorable

environment – binary

fission  Adverse environment – conjugation (sexual reproduction )

Binary fission

conjugation

Cell specialisation in multicellular organisms  Multicellular

organisms – begin – one cell (zygote)  Zygote – divide – embryo  Cell – grow – change shape – adapt to carry out specific function

 Tissues

– a group of cells which are similar in structure and are designed to perform specialized function – Eg. Muscle tissue

 Organ

– a group of tissues that cooperate closely to perform a specialized function  Eg. Stomach, liver

organ

tissue

cells

 System

– several organs that organized to carry out specific function

The necessity for cell specialisation and cell organisation  Cell

specialisation is important to multicellular organisms as complex organisms require various types of tissues, organs and system to function

 Without

cell specialisation, organisms will not be able to survive or sustain itself because there are millions of cells found in the body

 The

importance of cell specialization and organization : 1. Group of cells able to carry out specific function more efficiently

2. Division of labour enables organisms to carry out various task in an orderly and systematic manner

3. All living processes can be carried out more efficiently

4. Achieve a higher growth rate 5. Able to adapt and survive in diverse habitat

Cell organisation in human and animals  1. 2. 3. 4.

Tissues : Epithelial tissues Muscle tissues Connective tissues Nerve tissues

Epithelial tissues  Consist of one or more layer of cells  Tightly connected, little space between them

 Continuous

layer over body surface – skin, mouth

 Inner

lining cavities – digestive tract,

lung  Form glands

 Functions

: - protection, secretion, absorption - protection – infections, injuries, chemical,dehydration

- absorption – gas exchange in alveolus - lining of the small intestine

 Secretion

: – modification to form goblet cells which secretes mucus - glands – sweat gland, sebaceous glands

Muscle tissues  Composed of long cells called muscle fibers  Three types 1. smooth muscle – digestive tract, blood vessel, bladder, reproductive tract

2. Skeletal muscle 3. Cardiac muscle

 Smooth

muscle - involuntary actions of the body -food is move along the digestive tract

 Skeletal

muscle : - voluntary movement of the body

 Cardiac

muscle : - involuntary movement of the heart wall

Nerve tissues •Composed – neurons (nerve cells) •Specialised to transmit signal or nerve impuls

Connective tissues  Consist of various types of cells and fibre separated by extracellular matrix

Adipose tissue

 Examples

: tendons, ligaments, cartilage, bones, blood, lymph, adipose tissue

 Interwoven

with fibrous strands (collagen) with exception of blood and lymph

 Functions

: - bind structure together, provide and protection for other tissues

-

tendon – attach muscles to bones ligaments – attach bones to bones cartilage – provides to the nose

- bones – provide protections to organs - blood – regulating, transporting and protective functions

Organs  Organ

is formed by two or more types of tissues working together to perform particular functions  Examples - heart, skin, kidney

 Heart

-

– cardiac muscle connective tissue nerve tissue epithelial tissue

Cardiac muscle of the heart

Connective tissues

Skin  Act as a barrier against infections, physical trauma, water loss

Sweat pore epidermis Oil gland Dermis Erector muscle Nerve fibre Sweat gland

Blood capillaries Hair follicle

Adipose tissue

Malphigian layer

 Divided

into two main layer : - epidermis – mostly from dead epithelial cells - dermis –connective tissue, nerve tissue, epithelial tissue, muscle tissue

System  System

consist of several organs that cooperate to carry out a living process  11 major system in the body

 Major

systems : 1. Nervous system 2. Skeletal system 3. Circulatory system 4. Digestive system 5. Respiratory system 6. Excretory system

7. Reproductive system 8. Muscular system 9. Integumentary system 10. Endochrine system 11. Lymphatic system

 All

system combine to form multicellular organism

Assignment  Find

out the major organs/ tissues in each system  Find out the functions of each major system

Cell organisation in plants  Plant

cells also undergo specialization  Two types of plant’s tissue : 1. meristematic tissues 2. permanent tissues

Plant tissues

Meristematic tissues

Permanent tissues

Parenchyma tissue

Collenchyma tissue

Sclerenchyma tissue

Apical meristem

Meristematic tissues  Consist of small cells which have thin walls, large nuclei, dense cytoplasm, no vacuoles

 Young

and actively dividing cells which have not undergone differentiation  Apical meristems – at the tips of roots and the buds of shoots.

 Lateral

meristems / cambia – found in the peripheral areas of stems and roots

Permanent tissues  Permanent tissues consist of mature cells that undergoing differentiation or already undergone differentiation

 Three

types of permanent tissues: 1. Epidermal tissue 2. Ground tissue - parenchyma tissue - collenchyma tissue - sclerenchyma tissue

Epidermal Tissues

Permanent Tissues

collenchyma

sclerenchyma

Vascular tissues

parenchyma

3. Vascular tissue - xylem tissue - phloem tissue

Epidermal tissue  Outermost

layer  Cover the stems, leaves, roots, flowers, fruits, seeds

 Walls

of epidermis covered with waxy waterproof coating call cuticle

 Functions

: - prevent loss of excessive water through evaporation

- protects from mechanical injury - prevent diseases

 Root

– have root hairs for absorption of water  Specialised into guard cells which surround stomata

Parenchyma  Thin

walled cells, loosely arrange  Large vacuole

 Least

specialised, can be found in all organs of the plant

 Functions

: - store products of photosynthesis – sugar, starch

- specialised into palisade mesophyll cells and spongy mesophyll which contain chloroplast

- and shape to plants

Collenchyma  Elongated,

polygonal cells  Unevenly thick cell walls  Thickened by celulose and pectin

 Strong

and flexible

 Function

– to herbaceous plant, young stem, leaf stalk, petioles.

Sclerenchyma  More

rigid, cell walls thickened with

lignin  Mostly dead cells

 Functions

: - and strength - provides protection

Xylem  Consist

of tracheids and xylem vessel  Long tubes ed together end to end

 Cell

walls thickened with lignin

 Xylem

tissues dies upon reaching maturity

 Cytoplasm

disintegrated and left a hollow tube

 Functions

: - transport water from roots to leaves

- provides and mechanical strength

Phloem  Consist

of parenchyma cells, sclereids, sieve tubes, companion cells

 Conducting

cells are the sieves tube which have pores at both ends called sieve plates

 Sieves

tubes obtain nutrients a d energy from companion cells

 Functions

: - transports organic substances – carbohydrates, amino acids from leaves to storage organs and growing parts of plant

Plant tissue

Meristematic tissues

Apical meristems

Lateral meristems

Permanent tissues

Epidermal tissues

Vascular tissues

Xylem tissues

Phloem tissues

Ground tissues Parenchyma tissues

Collenchyma tissues

Sclerenchyma tissues

Organs and systems in plants  Plants

flower

organs – leaves, stems, roots,

 Flowering

plants have two main

systems : - root system – absorptive system

- shoot system – consist – stems, leaves, buds, flowers,fruits



system – stems, branches  Photosynthetic system – leaves (ground tissues, epidermal tissue, mesophyll tissue, vascular tissue )

 Reproductive

seeds)

system –flower ( fruits,

REGULATING THE INTERNAL ENVIRONMENT  Internal

environment is the conditions that exists within the body of an organism, with respect to the composition of the interstitial fluid

 Interstitial

fluid fills the space between the cells and constantly bathes the cells

Interstitial fluid Blood plasma

Nutrients and waste substances are exchanged between the interstitial and the blood plasma in the blood capillaries

 Nutrients

and waste substances are exchanged between the interstitial and the blood plasma in the blood capillaries

The

physical factors and chemical factors within the internal environment must be maintained at a constant level

Physical factors: - temperature, blood, pressure, osmotic pressure

 Chemical

factors : - salt, sugar, pH

The concept of Homeostasis  The

physical and chemical factors in the human body are controlled by a system called homeostasis

Homeostasis is the maintenance of a relatively constant internal environment for the optimal functions of the cells

 Mechanism

of homeostasis keep the physical and chemical factors of the environment in steady state

 Plants

needs lesser regulatory system : 1. Most plant cells are dead at maturity

2. Plants cells do not rupture in hypotonic environment because they have cell wall

 Physical

factor and chemical factors in animal body is constantly changing

 Example

– glucose level, pH, temperature

How homeostatic work  Blood

pressure increase  Homeostatic mechanism reduce the value to the normal level

 Blood

pressure decrease  Homeostatic mechanism increase the value to the normal level

 The

mechanism of homeostatic is called negative mechanism

 Positive

mechanism - the stimulus trigger a response that intensifies the initial change instead of reversing it to the original state