Cell structure and transport Flashcards
How have microscopy techniques developed over time?
Light ( 4)- developed? magnification amount and using what? level of cost and type of specimen magnified?
Electron (9)- developed? magnification amount, using what, to see what specifically? size, cost level, storage condition 3 requirements?
Light microscopes- developed mid 17th century- x2000 using beam of light. Cheap and can magnify live specimens.
Electron microscopes- developed in 1930s- x2million to see subcellular structures using beam of electrons. Large, expensive, require special temp, humidity, pressure controlled rooms. 2 types:
TEM- 2D images with high magnification and resolution.
SEM- 3D images but lower magnification and high resolution.
What are the differences in the magnification and resolution between a light and electron microscope.
Resolution/ resolving power is the ability to distinguish between two separate points.
light microscope- 200nm, SEM- 10nm, TEM-0.2nm.
how is the magnification, real size and and image size of a specimen calculated?
magnification= eye piece lens x objective lens magnification.
magnification = size of image/size of real object ( rearrange as needed)
What are the 5 main parts of an animal and plant cells?
nucleus- surrounded by nuclear membrane. Contains genes and chromosomes which carry instructions to make proteins needed to build new cells and organisms. 10micrometre diameter.
cytoplasm- liquid gels in which organelles are suspended in and chemical reactions take place.
cell membrane- controls glucose and mineral ion entry and urea and hormone exit.
mitochondria- aerobic respiration to release energy occurs here. Upto 2 micrometres in length and 0.7 in diameter.
ribosomes- the site of protein synthesis.
compare the similarities and differences between a plant and animals cell (3 organelles).
All plant cells have a cell wall made of cellulose for strength and support as well as:
chloroplasts- found in green parts of plants and contain chlorophyll. absorb light for photosynthesis hence roots cells do not have chloroplasts. 3-5 micrometres long.
permanent vacuole- for rigidity and support. Space in cytoplasm filled with cell sap (sugar and salt solution).
Describe an algal cells 3 main organelles and how it makes it food.
Photosynthesis so has chloroplasts, cell wall and nucleus.
Describe a bacteria cell and its 7 organelles- are they harmful?
single celled organisms-0.2-2 micrometers and 2 orders of magnitude smaller than a eukaryotic cell.
individual bacteria require a microscope although colonies of bacteria in their millions when cultured can be seen by the naked eye.
cell membrane
genetic material-free single loop of DNA in cytoplasm not enclosed in DNA.
cell wall- does not contain cellulose like in plants.
cytoplasm
slime capsule (protective)
plasmids- extra small rings of DNA for antibiotic resistance.
flagella- protein strands that lash around and aid movement.
some are useful and some are harmful to humans, other animals and plants.
how is order of magnitude worked out?
bigger number divided by small number to the power of the number of 0s after 1.
Describe a sperm cell and its 4 adaptations.
Released from male and may need to travel through water or female reproductive system to get to egg and pass on genetic information from male.
long tail- aids movement to reach destination.
mitochondria in high amounts in middle section to provide energy to tail.
acrosome- stores digestive enzymes for breaking down outer layer of egg.
large nucleus- genetic information contained to be passed on.
Describe a nerve cells and its 3 adaptations.
Nerve cells carry electrical impulses to different parts of the body.
1) lots of dendrites to make connection to other nerve cells.
2) axon- carries the nerve impulse (longest one in humans is from base of spine to toe).
3) nerve endings/synapses- adapted to pass impulses to another cell or between nerve and muscle cell using special transmitter chemicals and contain a lot of mitochondria to provide energy to make these transmitters.
Describe a striated muscle cells and its 3 adaptations
muscles cells are specialised to contract and relax and muscles contract in pairs to move bones.
special proteins that slide over each other making the fibres contract.
contain mitochondria- to transfer energy needed for the chemical reactions that take place as the cells contract and relax.
store glycogen- chemical that can be broken down and used in cellular respiration by the mitochondria to transfer the energy needed for fibres to contract.
Describe root hair cells and its 3 adaptations.
Found at the tip of growing roots and located close to xylem tissue.
take in water by osmosis and mineral ions by active transport.
xylem tissue carries water and mineral ions up to the rest of the plant.
1) increase surface area for water to move into cells.
2) large permanent vacuole- speeds up movement of water by osmosis from the soil across to the root hair.
3) have many mitochondria- that transfer energy needed for the active transport of mineral ions and root hair cells.
Describe a photosynthetic cell and its 3 adaptations.
chloroplasts- specialised green structures containing chlorophyll that trap light for photosynthesis.
positioned in outer layer of leaf and stem.
large permanent vacuole- cell rigid and when arranged help support stem and keep leaf spread out the collect light for photosynthesis.
Describe an xylem cell and are they dead or alive. Explain how it carries out it’s function.
carries mineral ions and water from roots to highest leaf and shoots and supports plant. Made up of xylem cells.
alive when first formed but lignin (special chemical) builds up in spirals of cell walls.
Cells die and form long hollow tubes that allow water and mineral ions to move through them from one end of the plant to the other.
The spirals and rings of lignin in the xylem cells make them very strong and withstand the pressure of water moving up the plant. Also help support the plant.
Describe a phloem cell and its 2 adaptations.
phloem cells make up phloem- specialised transport tissue which transport dissolved food made by photosynthesis around the body of the plant.
phloem does not become lignified and die.
1) cell walls break down to form special sieve plates to allow water carrying dissolved food to move freely up and down the tubes where it is needed.
2) phloem cells lose a lot of their internal structure but are supported by companion cells that keep them alive. The mitochondria of the companion cells transfer the energy needed to move dissolved food up and down the plant in phloem.
