Cell Structure and Cell Organisation

What is cell?Cell is the basic unit that build up organism.

What do you call the structures in a cell?The structures in a cell is called organelles.

State the organelles in an animal cells.Cell membrane, mitochondrion, rough endoplasmic reticulum, smooth endoplasmic reticulum, ribosome, centriole, golgi apparatus.

Animal Cell

1 2 3 4

5 6 7 8

Plant Cell

ch cw

ChloroplastCytoplasm

NucleusVacuole

Cell membrane

Cell wall (made ofcellulose)

Plant Cell

Nucleus

Endoplasmic Reticulum

Ribosome

Golgi Apparatus

Plasma membrane

Mitochondrion

Lysosome

Centrioles

Chloroplast

Cell Wall

Activity 2.1.2Draw a table to list the functions of organelles in animal cells and plant cells.

Organelles Functions

Organelle Functions

Cell membrane

Cell membrane forms a boundary to separate the content of a cell from outer environment.Cell membrane regulates the movement of substances into and out of the cytoplasm.

Cell wallCell wall gives shape to a plant cell.Cell wall provides mechanical support for the plant cells.

Cytoplasm Cytoplasm acts as a medium for biochemical reactions in the cell.

NucleusNucleus contains genetic information that determines the characteristics and functions of the cell.Nucleus controls all the activities which take place in the cell.

vacuoleVacuole regulates water balance in the cell.Vacuole acts as a storage place in a cell.

Task 2.1.2 Complete the below table to state the functions of each organelle.

Mitochondrion Mitochondria carry out cellular respiration to release energy in form of ATP.

Ribosome Ribosomes synthesise protein.

Endoplasmic reticulum

Rough ER transports proteins made by ribosome.Smooth ER is the site of metabolic reactions – synthesis of lipids and detoxification of drugs and poisons.

Golgi apparatus Golgi apparatus process, package and transport carbohydrates, proteins, phospholipid and glycoprotein.

Lysosome Lysosome contains hydrolytic enzymes to digest complex organic molecules.Lysosome eliminates worn out mitochondria and other damaged organelles.

Centriole Centriole functions during cell division in animal cells.

Chloroplasts Chloroplast traps sunlight and converts light energy into chemical energy during photosynthesis

You have learnt about the cellular components of animal and plant cells. Now, carry out a discussion among your group to compare and contrast the structure of animal and plant cells. You can present your findings by using table.

Activity 2.1.3

Animal Cell Plant Cell

CORRECTIONS

Similarities:Both animal cell and plant cell have a nucleus, a plasma membrane, cytoplasm, Golgi apparatus, mitochondria, rough endoplasmic reticulum, smooth endoplasmic reticulum and ribosomes.

Differences:

Animal Cell Plant CellAnimal cell does not have fixed shape / regular shape.

Plant cell has fixed/regular shape.

Animal cell does not have cell wall.

Plant cell has cell wall.

Animal cell does not have chloroplasts.

All green plants have chloroplasts.

Animal cell does not have vacuole or if have, vacuoles are usually small and numerous.

Mature plant cell has a large central vacuole.

Animal cell has centrioles. Plant cell does not have centrioles.

Animal cell stores carbohydrate in the form of glycogen.

Plant cell stores carbohydrate in the form of starch.

Unicellular Organisms

How does a unicellular organism perform its living processes?

•It depends on its cellular components which include the organelles.

Specification / Differentiation

Multicellular organisms are made up of many types of cells. The cells undergo specialisation to become specific in order to perform different function. Therefore, certain organelles are found abundantly in the specific cells.

For example, pancreatic cells which synthesise and secrete enzymes and hormones contain a high density of rough endoplasmic reticulum.

The density of organelles in specific cells

Cell organisation in multicellular organisms

Cells Tissues Organs

Systems Organism

Example of cell organisation in digestive system in a human

Cell organisation

Cell organisation in mammals

Cell organisation in plants

Cells Tissues

Organs Systems

OrganismMeristematic

tissues

Permanenttissues

Young, activelyDividing cells

Differention

thin walls,large nuclei,

dense cytoplasm,

no vacuoles.

Tips of roots and buds of

shoots

Mature tissues

Differention

are

haven’t

located at

have

are

have

epidermal tissues,ground tissues,vascular tissues.

consist of

Different types of cells in plants which have been undergone specialisation

Parenchyma• “typical” plant cells = least specialized•photosynthetic cells, storage cells• tissue of leaves, stem, fruit, storage roots

Collenchyma•unevenly thickened primary walls = support

Sclerenchyma•very thick, “woody” secondary walls = support•rigid cells that can’t elongate• dead at functional maturity

Plant cell types in tissues – Ground tissues

Vascular tissue•Transports materials in roots, stems & leaves

Xylem •-carry water & minerals upfrom roots•tube-shaped dead cells•only their walls provide a systemof microscopic water pipes

Phloem•carry nutrients throughout plant•sugars (sucrose), amino acids…• tube-shaped living cells

Regulating the internal environmentCells bathe in the internal environment which contain interstitial fluid.

The internal environment must be regulated to maintain its level. Do you know why?

The constant internal environment ensure the cells to function optimally.

The process involves in maintaining the balance of internal environment is called ………………………….homeostasis

Which type of mechanisms involves in homeostatic mechanism?

Corrective mechanism

Normal value (set point)The value

drops below the set point

Corrective mechanism

The negative feedback mechanism

Normal value (set point)

The value rises above the set point

Vacuole

Sample Answer : Compare and contrast animal cell and plant cell

Animal Cell Plant Cell•Both animal cell and plant cell have plasma membrane, nucleus, cytoplasm, ribosomes, endoplasmic reticulum, Golgi apparatus and mitochondrion.

•Animal cell has centriole and lysosome.

•Plant cell does not have centriole and lysosome.

•Animal cell does not have cell wall, large central vacuole, and chloroplast.

•Plant cell has cell, wall, large central vacuole, and chloroplast.

•Animal cell has irregular shape. •Plant cell has regular / fixed shape.

•Animal cell stores carbohydrates in the form of glycogen.

•Plant cell stores carbohydrates in the form of starch.

Sample Answer: By giving appropriate examples, describe how different organelles work together to enable the cell to function in an orderly manner.

Pancreas cell functions to produce enzyme. To produce enzyme, ribosome sends mRNA messenger to nucleus to copy DNA code. mRNA messenger returns to ribosome. Ribosome synthesise proteins based on the code. Proteins enters rough endoplasmic reticulum and is enclosed in vesicle. Vesicle with proteins fuses with Golgi apparatus. The proteins is modified to form specific enzyme. Then, the enzyme is enclosed in secretory vesicle. The secretory vesicle will fuse with plasma membrane and releases the enzyme out from the cell.