PREPARED BY:
Ahmad Ikmal ‘Akif bin Abdul Khalil
4 UTM
2.1 CELL STRUCTURE AND FUNCTION
Living organisms are made of basic units called cells.
Living component of a cell is called protoplasm which is consists of cytoplasm and nucleus.
The protoplasm is surrounded by a thin layer of plasma membrane.
Both animal and plant cells have these components.
PLANT CELLS ANIMAL CELLS
CELL MEMBRANE CELL WALL
•The membrane at the surface which encloses the content of a cell-plasma membrane.
•It regulates the movement of substances into and out of the cytoplasm.
• Rigid outer layer that surrounds the plasma membrane of plant cells.
• Functions :
1. gives shape to a plant cell
2. provides mechanical support for plant cell
3. Protects the plant cell from rupturing due to the excessive intake of water.
CYTOPLASM NUCLEUS
•The region between the nucleus and the plasma membrane.
•Contains organic and inorganic substances and acts as a medium for biochemical reactions in cell.
•Function : provides substances obtained from the external environment to the organelles.
•Appears as large,dense,spherical organelle enclosed by a nuclear membrane.
•Contains nucleoplasm and dark spherical structure called nucleolus.
•Function : controls all the activities which take place in the cell.
VACUOLE MITOCHONDRIA
•A fluid-filled sac which surrounded by tonoplast.
•The fluid contained in a vacuole-cell sap
•Function : acts as a storage place in a cell.
•The cell sap in a vacuole supports herbaceous plants.
•Appear in electron micrographs
•Involved in cellular respiration- releases energy when food substances such as glucose are broken down with the help of enzymes present in the mitochondria.
RIBOSOME ENDOPLASMIC RETICULUM
• Compact spherical organelles found attached to the surface of rough endoplasmic reticulum.
• Functions :
1. Synthesis protein
2. Use information carried by the chromosomes to make these proteins
•Two types of emdoplasmic reticulum:
Rough endoplasmic reticulum –transports proteins made by the ribosomes
Smooth endoplasmic reticulum – the site of important metabolic reactions,including synthesis of lipids and detoxification of drugs and poisons.
GOLGI APPARATUS LYSOSOMES
•Consists of a stack of flattened membranous sacs
•Function : processing, packaging and transporting centre of carbohydrates, proteins, phospholipids and glycoproteins.
•Are membrane-bound sacs that contain hydrolytic enzymes.
•These enzymes digest or break down complex organic molecules such as proteins and nucleic acids.
•Also digest bacteria by breaking down the bacteria cell wall.
CENTRIOLES CHLOROPLAST
•Are a pair of small cylindrical structures located just outside the nucleus.
•Are composed of a complex arrangement of microtubules.
•Typically lens-shaped
•Chloroplasts contain the green pigment which is called chlorophyll.
•Chlorophyll traps sunlight and converts light energy into chemical energy during photosynthesis.
COMPARISON BETWEEN THE STRUCTURE OF ANIMAL AND PLANT CELLS
SIMILARITIES
ANIMAL CELLS PLANT CELLS
Nucleus Present Present
Cytoplasmic streaming
Present Present
Ribosomes Present Present
DIFFERENCES
ANIMAL CELLS PLANT CELLS
Chloroplast Animal cells don't have chloroplasts
Plant cells have chloroplasts
Plasma Membrane Yes; only cell membrane Yes; cell wall and a cell membrane
Centrioles Always present Only present in lower plant forms
Lysosomes Lysosomes occur in cytoplasm
Lysosomes usually not evident.
Vacuole One or more small vacuoles (much smaller than plant cells).
One, large central vacuole taking up 90% of cell volume.
Shape Round Rectangular
Cell wall None Yes
TYPES OF CELLS FUNCTIONS ORGANELLES FOUND ABUNDANTLY IN THE SPECIFIC CELLS
SPERM CELLS
Require large amounts of energy to propel towards the uterus and Fallopian tube during fertilisation
Mitochondrion
FLIGHT MUSCLE CELLS IN INSECTS AND
BIRDS
Contract and relax to enable movements and flight
Mitochondrion
CELLS IN THE MERISTEMS
To enable cells in the meristem divided by mitosis process
Mitochondrion
MESOPHYLL PALISADE CELLS
Absorb sunlight during photosynthesis Chloroplasts
RELATING THE DENSITY OF CERTAIN ORGANELLES WITH THE FUNCTIONS OF SPECIFIC CELLS
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