Cell Structure Flashcards
What are cells?
The basic units of all forms of life
Cells come together to form communities
What are eukaryotes and what do they contain?
Eukaryotic cells have cytoplasm, cell membrane, nucleus with genetic material
Plant and animal cells are eukaryotes
Eukaryotes evolved from prokaryotes perhaps 1.5-2 billion years ago
What are prokaryotes and what do they contain?
Bacterial cells are prokaryotic
Smaller in comparison 1000-10000 times smaller
Cytoplasm and membrane surrounded by a cell wall
Genetic material not enclosed in a nucleus
It is a singe DNA loop and maybe more DNA rings called plasmids
What do most animal cells contain?
Nucleus Cytoplasm Cell membrane Mitochondria Ribosomes
What do plant cells also contain?
Chloroplasts
Permanent vacuole filled with cell sap
A cell wall made of cellulose strengthening the cell
What are the common specialised animal cells?
Sperm
Nerve
Muscle
What are the common specialised cells in plants?
Root hair cells
Xylem
Phloem
What is cell differentiation?
As an organism develops cells differentiate to form different types of cells
Most types of animal cells differentiate at an early stage
Many types of plant cells retain ability to differentiate throughout life
Why do cells differentiate?
To perform specialised functions
In mature animals cell division is mainly retracted to repair and replacement
A differentiated cell acquires different sub cellular structures so it can carry out specific functions
Explain the purpose of the root hair cell?
Close to the tips of growing roots
Plants take in water through them, large surface area and thin walls
Explain photosynthetic cells?
Contain chloroplasts
Continuous layers in leaves or stem to absorb sunlight
Large vacuole keeps cell rigid through osmosis
Explain xylem cells?
Transports water or mineral ions from roots to leaves
Cells fill with lignin and die making hollow tubes
Spirals of lignin make cell wall strong
Explain phloem cells?
Transport tissues carrying food
Spiral cells
Cell walls break down to make sieve plates
Supported by other cells
Explain sperm cells?
Long tail full of mitochondria to make tail work
Acrosome stores enzymes
Large nucleus with genetic information
Explain nerve cells?
Carry electrical impulses
Lots of dendrites to join with the nerve cells
Axon carries nerve impulse along body and has lots of mitochondria
Explain muscle cells?
Straightened cells contract and relax in pairs Contains special protein that contracts Many mitochondria for energy transfer Stores glycogen Used in cellular respiration
What does a vacuole contain?
Cell sap
What does cellulose do?
Forms cell walls and keeps cells in rigid shape
What do chloroplasts contain and what do they do?
Contain chlorophyll
Make food through photosynthesis
What is the role of a cell membrane?
Holds cell together
Controls what goes in and out of the cell
What does cytoplasm contain?
Enzymes - cytoplasm is where chemical reactions happen
What controls the cell and what is the exception in animal cells?
Nucleus
Red blood cells
What is different about bacteria cell?
Prokaryotes cells - means before nucleus 1000-10000 times smaller than eukaryotes Much simpler Has genetic material Plasmids Cytoplasm Cell membrane Cell wall Flagella Slime capsules
How are leaves adapted for photosynthesis?
Waxy cuticle - prevents water loss
Spongy mesophyll - not tightly packed together but allows CO2 and has irregular cells
Guard cell and stomata are specialised doors so CO2 and O2 can’t diffuse into leaf - on bottom of the leaf to limit water loss
Xylem and phloem - move water/solutes and food from leaves to plant
Palisade - lots of chloroplasts, block shaped, catch sunlight for photosynthesis, packed into layers
