Cells Flashcards
What does the nucleus do?
Contains DNA and controls the activities of the cell
What does the cell membrane do?
Controls what goes in and out of the cell
What does the mitochondria do?
Where aerobic respiration occurs-releases energy
What do the ribosomes do?
Where proteins are made via protein synthesis
What does the cytoplasm do? (Plant)
Where chemical reactions happen
What does the chloroplast do? (Plant)
Contains chlorophyll to absorb sunlight. Where photosynthesis happens
What does the vacuole do? (Plant)
Keeps the cell rigid supports it and stores sap
What does the cell wall do? (Plant)
Made of cellulose for support and to stop the cell from bursting
What does the chromosonal DNA do? (Bacteria)
Controls most of cell activities
What does plasmid DNA do? (Bacteria)
Controls some of the cell activities
What does the flagella do? (Bacteria, tail)
Propels to move the cell
What does the slime coat do? (Bacteria)
Stops the cell drying out
What does the acrosome do? (Sperm, head)
Contains enzymes and it breaks down the eggs jelly coat to fertilize it
What does the cytoplasm do? (Egg cell)
It contains lots of nutrients for the fertilized egg to develop
What is mitosis?
Mitosis is the production of 2 genetically identical diploid daughter cells
What are the stages of mitosis in order?
Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
What happens in the interphase?
New sub-cellular structures are made and the DNA replicates
What happens in the prophase?
Nucleus breaks down and spindle fibres begin to form
What happens in the metaphase?
Spindle fibres attach to the chromosones and the chromosones line up against the equator of the cell
What happens in the anaphase?
The spindle fibres shorten and pull the chromosones apart to the poles of the cell
What happens in the telophase?
A membrane forms around each set of chromosones to form 2 new nuclei
What happens in cytokinesis?
New cell surface membranes form to seperate the 2 genetically identical diploid daughter cells
How is there growth in plants?
Cell division by mitosis in shoot and root tips
Elongation-cells in shoots and root tips get longer
Differentiation-meri stem cells can differentiate into different cells
What are the characteristics of ciliated epithial cells?
Have cilia (hair like structures) that waft the fertilised egg towards the womb Contain a lot of mitochondria to release a lot of energy from aerobic respiration to move the cilia
Facts about electron microscopes
What does higher resolution mean?
Higher magnification and resolution than a light microscope
Higher resolution means that we can see in more detail
What happens to an enzyme when it reaches optimum temperature?
The enzymes active site shape changes so much that it denatures the enzyme and so the substrate can no longer bind to it and the reaction stops
What is diffusion?
Diffusion is the passive movement of molecules from an area of high concentration to an area of low concentration.
What is active transport?
The movement of molecules from an area of low concentration to an area of high concentration using energy from respiration so transport proteins can carry the molecules across the membrane
What is osmosis?
Passive movement of water molecules from an area of high concentration to an area of low concentration across a partially permeable membrane
How many chromosones in a haploid cell?
23
How many chromosones in a diploid cell?
46
Why is mitosis important to organisms
Asexual reproduction
Growth
Repair
How is there growth in animals
Cell divison by mitosis
Differentiation - only stem cells can differentiate into other cell types
Facts about stem cells
They are undifferentiated not specialised
Can divide by mitosis to make specialised cells
Embrionic stem cells can become almost anything
Adult stem cells only have a limited range of cell types
What are the benefits to embrionic stem cells?
Easy to collect and can treat more diseases
What are the drawbacks of embrionic stem cells?
Ethical issues of destroying embryos to get stem cells
Stem cells could get rejected by the bodys immune system
What are the benefits of adult stem cells
No ethical issues
What are the drawbacks of adult stem cells?
Difficult to collect from the body
Can only treat a range of diseases
What is the central nervous system (CNS) made of?
Brain and spinal cord
What are the 3 types of neurones?
Sensory neurone
Relay neurone
Motor neurone
What does the sensory neurone do?
Carry impulses from the receptors to the CNS
What does the myelin sheath do?
Speeds up transmission of electrical impulse
What does the relay neurone do?
Carry impulses from the CNS to the motor neurones (relay neurones make up the brain and spinal cord)
What does the motor neurone do?
Carry impulses from the relay neurone to the effectors
What is a synapse
Synapes are gaps between neurones that convert electrical energy from the impulse in the neurone into chemical energy in the synapse. Chemicals called neurotransmitters diffuses across the synapse and cause a new electrical impulse in the next neurone
What happens in a reflex arc?
A stimulus is sensed by a receptor which sends an electrical impulse up the sensory neurone. The impulse is converted to a chemical signal at the synapse. Neurotransmitters diffuse across the synpase and pass the signal to the relay neurone (in the spinal cord). The signal crosses another synapse to reach the motor neurone which takes it to the effector, which produces a response.
What happens in meiosis?
Makes 4 genetically different haploid gametes
The cytoplasm divides twice
