Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 6 Model Of Cells The Basic Units Of Life - Coggle Diagram
Chapter 6 Model Of Cells
The Basic Units Of Life
What are cells?
All organisms are made up of tiny building blocks called
cells
.
Bacteria are
unicellular
organisms. They can be spherical, rod or spiral-shaped.
Most plants and animals are made of many cells.
Organisms that are made up of many cells are known as
multicellular
organisms.
Microscopes are used to study cells as they are too small to be seen by the naked eye.
Microscopes enlarge the size of the cells so that we can see them more clearly.
Cells exist in a variety of shapes and sizes according to their functions.
Diversity of cells can be simplified by classifying them according to similarities in their structure.
Cells that are representatives of each category are called typical cells.
A typical cell serves as a cell model that can be used to explain the cells various structures and functions.
It helps us explain and understand processes occuring in organisms.
What is inside a typical cell?
side note
Scientists can easily study the parts of a cell, scientists can identify possible diseases or disorders in a person.
It also allows us to determine whether a cell is an animal or plant cell.
Plant cell
Cell wall
Thick layer surrounding the cell membrane
Consists of a type of carbohydrate called cellulose
Supports the cell and gives it a regular shape
Chloroplast
Contains the green pigment, chlorophyll. The plant needs chlorophyll to absorb energy from the sun to make food through photosynthesis
These are just the extra parts that are in a plant cell but not in a animal cell. Everything a animal cells has, a plant cell has.
Animal cell
Nucleus
-Spherical-shaped
-Responsible for reproduction
-Controls cell activities including repair of worn-out parts
-Keeps the cell alive
-Contains genetic material called chromosomes
Chromosomes
-Long thread-like structures found in the nucleus
-Contains genes that carry genetic materials that determine heredity
-Passed down from parents to offspring
Vacuoles
-Fluid-filled space within the cytoplasm, surrounded by a membrane
-Contains water and other nutrients needed for the organisms to survive
-Usually small, numerous and temporary in an animal cell
-Usually a single large space surrounded by a membrane in a plant cell
-Contains a liquid called cell sap ( in a plant cell ). Cell sap is made up of water and dissolved materials such as sugars and mineral salts.
Cytoplasm
-Jelly-like substance
-Contains chemicals and organelles that carry out special functions
-Serves as the site where many chemical reactions take place
Cell membrane
-Thin membrane surrounding the cell
-Partially permeable structure that only allows certain substances to pass through
-Serves as a boundary between the cell and the external environment
-Controls substances entering or leaving the cell
Forming a multicellular organism
How are cells organised into tissues, organs and organ systems in multicellular organisms?
Multicellular organisms such as humans are made up of many organised parts.
Cells with specific functions are organised into tissues.
Tissues are in turn grouped into organs.
Organs are then grouped into organ systems.
Most cells in multicellular organisms have specific functions
Heart muscle tissue
Along with blood vessels, nerve tissues and connective tissues,
they collectively form an organ called the
heart
.
Function of heart
Pumps oxygen-rich blood to all the cells in the body.
Side note
Human body
The circulatory system works with other organ systems to ensure that the human body functions properly.
Examples of organ systems in the human body: respiratory system, nervous system, excretory system, reproductive system and digestive system.
Several organs with related functions work together for specialised purpose as an
organ system
.
Example
Circulatory system
: The heart, arteries and veins work together to enable the organism to function properly.
Different types of tissues that work together to perform a function form an organ.
Heart muscle cells form heart muscle tissues. This tissue contracts and relaxes rhythmically.
Heart muscle cells
A single one contracts and relaxes rhythmically at a steady rate.
How do cells work together in a plant?
Palisade Mesophyll
cell
Long and cylindrical cell, contains numerous chloroplasts.
Chloroplasts contains chlorophyll to absorb sunlight for photosynthesis.
Palisade Mesophyll
tissues
Many palisade mesophyll cells packed together at the upper layer of the leaf to absorb maximum amount of sunlight for photosynthesis.
A leaf is an
organ
Different types of leaf tissues form a leaf .
A piece of leaf contains many different types of tissues, mesophyll tissues, xylem tissues, phloem tissues, epidermal tissues. These tissues work together to make food for the plant.
Organ system
Root system
The root takes in water and dissolved minerals from the soil into the plant.
Shoot system
The shoot system transports water to the leaf where it is required for photosynthesis. The leaves, stems and roots are organs that form the transport system of a plant.
The root and shoot systems work together to help the plant grow and function properly.
Division of labour
The breakdown of work into small and specific tasks for maximum efficiency.
Each part of a cell has a different function.
Division of labour in multicellular organisms
Division of labour is also carried out in a multicellular organisms as a whole.
In multicellular organisms, work is divided among each type of cell, tissue and organ.
For example, different organs in the body play important roles to ensure that our muscle cells obtain sufficient oxygen and energy during a game of badminton.
The lungs in our respiratory system allow us to take in oxygen needed to release energy from the food we eat.
The heart in our circulatory system pumps blood around the body. The red blood cells in blood transport oxygen to all parts of the body.
The muscle tissue in our muscular system uses the released energy to contract and relax so that we can move about.
