Level of organisation and Cell structure Flashcards
Tissue
A group of same/similar cells with a similar structure and function working together to carry out a particular job.
Organ
A collection of different tissues working together to carry out a particular job.
Organ system
A group of different organs that work together to carry out a particular job.
Cell differentiation
Enables the bodies of multicellular organisms to develop in many different ways enabling many different body forms. E.g. muscle cells enable some animals to rapidly move, whilst palisade cells enable plants to make food via photosynthesis.
Nucleus
Controls the activities of the cell and contains DNA/chromosomes/genes.
Cytoplasm
Site of metabolic reactions.
Cell membrane
Controls the passage of substances into and out of the cell.
Ribosomes
Site of protein synthesis
Mitochondria
Site of aerobic respiration to release energy.
Chloroplasts
Site of photosynthesis. Absorb light energy to make food. Contain chlorophyll.
Cell wall
Keeps the cells shape and keeps the cell rigid. Supports the cell.
Permanent vacuole
Helps keep the cell turgid (swollen). Contains cell sap.
Stem cells
Found in human embryos and adult bone marrow.
Yet to differentiate.
Capable of differentiating into any type of specialised cell that makes up the body.
what is the level of organisation for organs ?
cells
tissues
organelles
organs
organ system
what are examples of plant tissues ?
xylem tissue, phloem tissue
examples of organs in humans and plants ?
Humans: lungs
Plants: Leaves
what are the subcellular structures that are found in both plant and animal cells?
- cell membrane - controls which substances enter and leave the cell
- cytoplasm - a gel like substance where most of the chemical reactions happen
- ribosomes - where protein synthesis occurs
- mitochondria - site if respiration
- nucleus - contains the cell’s genetic ,material and controls the activity of the cell
what are the subcellular structures only found it plants?
cell wall - made of cellulose and provides structural support and strength
vacuole - contains sap which is a weak solution of sugars and salts
chloroplast - contains chlorophyll which absorbs the light needed for photosynthesis and its the site of photosynthesis
what do bacteria cells have instead of a nucleus?
circular strand of DNA that floats freely in the cytoplasm and has no membrane
name any other structures only present in bacterial cells
1 flagellum - used for locomotion
2 plasmids - small closed circles of DNA
examples of specialised cells?
nerve cell
muscle cell
sperm cell
root hair cells
how are nerve cells specialised
- a long axon to cover more distance
- branched connections at the ends which allow the nerve cell to connect and form a network through the body
- covered with a fatty sheath which insulates the cell and speeds up the nerve impulse
how are muscle cells specialised?
- contain proteins that slide over each other and make the fibres contract
- contain many mitochondria to transfer energy needed for chemical reactions to occur
- store glycogen which can be broken down and used in cellular respiration by the mitochondria to provide energy needed for fibres to contract
how are root hair cells specialised?
- increased surface area for water to move into the cell
- permanent vacuole that speeds us movement of water by osmosis from the soil across the root hair cell
- many mitochondria to transfer energy needed for active transport
