Organisation of cells Flashcards
(23 cards)
Unicellular prokaryotic
Composed of one cell
3.5-4 billion years old.
Lack of organelles or simple structure.
Unicellular Eukaryotic
More efficient because of the specialised organelles.
Unicellular general
Always exposed to the external environment
high surface area to volume ratio
Waste can be efficiently removed.
Colonial organisms
Group of identical single celled organisms, called a colony.
All individual cells can exist as single celled organisms.
Some colonised organism do contain specialised cells.
Volvox
Aton Van Leevwenhoek discovered the Volcoc as a colony of algae cells. They are usually between 500-600000 algae cells. Each cell has a red eyespot that is attracted to light. Contain chloroplasts however some get what they need via nutrients. They contain some specialisation however lacks tissues and organism thus a unicellular colony.
Multicellular organisms
Many different types of cells.
They all have a specialised functioning and the cells cannot live independently of each other. As a whole they have a smaller SA:V ratio and hence passive transport is insufficient and systems are developed such as respiratory and digestive.
Young embryonic cells only when matured are then specialised.
However organism contain various small cells which is then highly efficient for diffusion and osmosis.
Specialised cells
When a cell becomes specialised they are to differentiate and develop suitable structural features for their function. They originate from stem cells which are undifferentiated.
Stem cell examples
Embryonic stem cell
Stem cell human brain
Blood producing found in bone marrow.
Function of a specialised cell
All cells have genetic material, only some genetic material is used and what is used is dependent on the location in the body.
Specialised cells cannot develop into other cells
Cells working together
Specialised cells cannot function independently. Chemical secretion and nerve cell transmission are crucial to relay messages
PLants: Communication via chemical and physical contact.
Cell structure and function of Haemoglobin
Cells need a structure that makes their function more efficient. They may be flattened or elongated.
Haemoglobin transport oxygen around the body. They have a bioncan shape which allows them to have a higher SA:V ratio. Which equals the rapid diffusion of oxygen.
The tiny size means they can fit into capillaries.
No nucleus or organelles
High haemoglobin to bind with oxygen.
Structural organisation
Organelles
Cells
Tissues
Organ
Organ systems
Organisms
4 main Animal cell tissues
Epithelia, connective, nervous, and muscles
Epithelial
Covers the body’s surfaces
Protects organs
Forms glands
Barriers to injuries and infection
Abosption and secretion
2 distant surfaces
1. Exposed to exterior body cavity
2. Exposed to adjacent tissue
Cheel cell and intestinal cells.
Connective tissue
Made of protein fibres and elastin for flexibility.
Provides support
Binds cells and organs together
Integration of body parts
Vary in density between cells
Adipose tissues and cartilage tendons.
Nervous tissue
Communication between all parts of the body. Long dendrites and axon which creates a high SA to receive electrical messages.
Muscles tissue
Skeletal:
Has striations
Attached to bones
Contraction causes movement
Voluntary–> Recquires conscious thought to action.
Cardiac: Present in the heart
Connection junctions that are necessary for the heartbeat.
Involuntary.
Smooth muscles:
Pushes substances through organs, involuntary
Plant cell systems
Shoot systems:
Above ground, enables transport, exhange of gases, photosynthesis, reproduction. Leaves, stem and reproductive organs.
Root systems:
Part of the plant below ground, absorbs water and nutrients. Roots and root hairs.
Vascular system: Made up of Xylem and Phloem
Plant tissues
Meristematic, Dermal, Vascular and Ground
Meristematic
Found at the roots and shoots. Divid and provides new growth. Unspecialised cells. Cubed shaped and very small.
Dermal
Outer layer of stems, roots and leaves. Protects from damage. Secretes waxy layer. (Cuticle)
Apex of roots.
Vascular tissue
Transport of substances
2 main types 1:
Xylem: Water and salts
Phloem: Products of photosynthesis
Occurs in the roots, stems and leaves
Ground tissue
Internal cells of a plant
Food storage
Support
Photosynthesis.
