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2.1.3 Relation between the Density of Organelles and the Function of Cells

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Density of Organelle

  1. Density of organelle is refering to the abundance of certain organelles found in a cell.
  2. The density of an organelle in a cell is related to the specific function of the cell.
  3. Below are examples of high density of certain organelle and their reason.

Cell with high density of chloroplast.

Palisade mesophyll cell
Reason:
To trap sunlight to synthesise carbohydrate during photosynthesis.


Cell with high density of mitochondria

Sperm cells
Reason: Need energy to move through the uterus towards the Fallopian tubes.


Muscle cells
Reason: Contraction of muscle during movement need a lot energy


Meristem Cells
Reason: Meristem cells in the plant shoots and roots are involved in cell division to produce new cells for growth. It needs a lot of energy for the activities.

Cell with high density of endoplasmic recticulum

Cells in salivary gland
Reason: Active in synthesing and secreting digestive enzyme

Pancreatic Cells
Reason: Active in synthesing and secreting hormone and enzyme

2.1.2 Comparison between the Animal Cell and Plant Cell

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Similarities of Animal Cell and Plant Cell

  1. Both animal cells and plant cells have
    1. plasma membrane
    2. nucleus with nucleic bounded by nuclear membrane
    3. cytoplasm
    4. ribosome
    5. mitochondria
    6. golgi apparatus
    7. endoplasmic recticulum



Differences between Animal Cells and Plant Cells

Animal Cells Plant Cells
Cell Wall Absent Present
Cytoplasm Present throughout the cell. Present, but usually confined to a thin layer at the edge of the cell.
Chloroplast Absent Present
Vacuole Present in some animall cells. Normally small and distributed throughout the cell. Present. Large and filled with cell sap.
Nucleus Normally in the middle of the cell Normally at the edge of the cell
Lysosome Present Normally absent
Centriole Present Absent
Storage Granule Mainly as glicogen Mainly as starch
Shape Do not have fixed shape Have fixed shape
Size Usually smaller than plant cell Usually bigger than animall cell
Cilia and Flagella Present (Usually) Absent
Secretion Produces a variety of secretions. Produces few secretions.

2.1.1 Components of a Cell

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  1. Each cell consists of a plasma membrane and protoplasm
  2. The protoplasm consist of cytoplasm and nucleus.
  3. Cytoplasm contains many types of organelles.
  4. The following is the illustration of the animal cell and plant cell.
(Animal Cell)


(Plant Cell)

Non-Organelle

Plasma Membrane

  1. The plasma membrane separates the content of the cell from its external environment.
  2. It regulates the movement of substances entering and leaving the cell.
  3. It also allows the exchange of nutrients, respiratory gases and wastes products between the cell and its environment

Cytoplasm

  1. The cytoplasm contain variety of organelle.
  2. The function of the cytoplasm is to maintain the shape of the cell.
  3. It acts as a medium for the biochemical reactions occur within the cell
  4. It also store chemical substances such as glicogen granules (in animal cells), starch granules (inplant cells) and enzymes.


Cell Wall

  1. The cell wall only contain in plant cell. It support the cell and the plant and maintain the shape of the cell.
  2. It also prevents the cell from bursting when too much water enters the cell through osmosis.
  3. It allows substances to move through it.

Nucleus

  1. The nucleus contains the genetic material of a cell.
  2. It controls the activities of the cell.
  3. It also produces ribosomes and ribonucleic acids(RNA).

Organelle

Endoplasmic Recticulum (ER)

- Rough Endoplasmic Recticulum:

  1. Transporting the newly synthesised protein.
  2. Involve in the systhesis of protein.
  3. Provides surface for chemical reaction

- Smooth Endoplasmic Recticulum:

  1. Transporting lipids and glycerols.
  2. Synthesising lipids and other non-protein substances.

Mitochonrion

  1. Produces ATP (Adenosine triphosphate.)
  2. Site of energy production through cellular respiration.

Ribosomes

  1. Site for synthesising protein.
  2. Golgi Apparatus
  3. Site for the production of enzyme andlysosome.
  4. Produces polysacharides, glycoproteins andsecretory enzyme.
  5. Storing and modifying carbohydrate and glycoprotein.
  6. Transport and store lipid.

Vacuole

  1. Stores food (Carbohydrate, amino acid) and water.
  2. Support herbaceous plants when it is turgid.
  3. Stores organic waste (in leaf cells).

Chloroplast

  1. Contain chlorophyll and hence a site for photosynthesis to take place.

Centrosome


  1. The centrosome is served as the main microtubule organizing center (MTOC) of the animal cell as well as a regulator of cell-cycle progression.
  2. It form spindle fibres during cell division in animal cell.


Lysosomes


  1. Lysosomes contain hydrolytic enzymes that digest or break down complex organic molecules such as proteins, polysaccharides and lipids.
  2. The enzymes eliminate worn out organelles and damaged organelles.

Golgi Apparatus


  1. The golgi apparatus processes proteins and lipids from the endoplasmic reticulum
  2. The products are sorted by the Golgi Apparatus and packaged into vesicles
  3. The vesicles then release their contents outside the cell.
  4. It also responsible to the formation of lysosomes.

2.1 Cell Structure and Function

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Theory of Cell

  1. The cell is the basic unit or building block for all living organisms.
  2. All organisms are made up of one or more cells .
  3. Cells are the fundamental and structural unit of life.
  4. A cell is made up of a plasma membrane which contains protoplasm.
  5. Protoplasm is made up of cytoplasm and a nucleus.
  6. A cell consist of the non-organelle structure the organelle structure.

Non-organelle/Organelle Structures of Cell

  1. The non organelle structure of a cell include
    1. Plasma membrane
    2. Cytoplasm
    3. Cell wall (plant cell only)
  2. Whereas the organelle structure of a cell include
    1. Nucleus
    2. Endoplasmic Recticulum
    3. Mitochondrion
    4. Ribosom
    5. Golgi apparatus
    6. Vacuole
    7. Chloroplast (plant cell only)

    Structure of an Animal Cell


    1. Each animal cell is enclosed by a plasma membrane.
    2. Within the plasma membrane is the protoplasm which consists of the cytoplasm and a nucleus.
    3. Animal cells do not have regular shapes.
    (This file is shared under GNU Share Document Licence from  Wikipedia)


    Structure of a Plant Cell


    1. Each plant cell is enclosed by a plasma membrane which is protected by a cell wall.
    2. Again, within the plasma membrane has a nucleus and cytoplasm.
    3. Unlike animal cell, most plant cells have chloroplasts which contain chlorophyll.
    4. Also, a mature plant cell may have a large vacuole which contains cell sap.
    5. Plant cells have a fixed shape because they have cell walls.
    (Onion Cell)

    1.2 Scientific Investigation

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    Scientific Method

    Scientific method is a body of technique of acquiring knowledge about the nature and its phenomena.

    Basics Steps of Scientific Investigation

    1. Identifying problem
    2. Making hypothesis
    3. Plannig the investigation
    4. Identifying and Controlling Variable
    5. Conducting the experiment
    6. Collecting and recording data
    7. Analysing and interpreting data
    8. Making conclusion
    9. Preparing the report


    The 2 main scientific skills

    1. Science process skill (Mental skill)
    2. Manipulative skill (Hand skill)


    The 6 Science Process Skill (OCCMIP)

    1. Observation
    2. Communication
    3. Classification
    4. Measurement
    5. Inference
    6. Prediction


    Examples of Manipulative Skill

    1. Handling apparatus and material correctly.
    2. Handling specimen correctly
    3. Clean apparatus correctly
    4. Storing apparatus and reagents correctly


    Hypothesis

    Hypothesis is a suggested explanation for a specific phenomenon.

    Inference

    Inference is the act or process of deriving a conclusion based on what one already knows.

    Variable

    Variable is a quantity whose value may change in an experiment. It is the parameter that may influence the outcome of an experiment or the data been collected in the experiment.

    1.1 The Study of Biology

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    Biology is the study of life or living organisms.
    bios - life
    logy - (original: logos) which means study.

    Importance of Biology

    1. better understanding on the functions of human body.
    2. better understanding on the causes of diseases and its cure.
    3. better understanding on ecology and henceimprove the management of problems related to the environment.
    4. saving animal and plant species which arefacing extinction.


    Fields of Biology Research

    1. Anatomy
    2. Physiology
    3. Cell biology
    4. Molecular biology
    5. Genetics
    6. Microbiology
    7. Bacteriology Entomology
    8. Developmetal biology
    9. Ecology
    10. Zoology
    11. Botany
    12. Taxonomy
    13. Histology

    Career Related to Biology

    Medicine Doctor, nurse, dentist, pharmacist, veterinarian, physiotherapist
    Biotechnology Biotechnologist, nutritionist, food technologist
    Agriculture Estate manager, botanist, agricultural officer
    Industry Research officer, scientist

    Characteristic of Living Organism

    Metapolism: Obtain energy for life and activities
    Respiration: Breakdown food to obtain energy for growth, movement....
    Nutrition: -Sources of energy and growth
    -Repair dameged tissue
    Locomotion: Moving from place to place (only for animal)
    Reproduction: Reproduce offspring
    Growth: Increasing in size
    Excretion: Expelled waste from body