B1 Cells Flashcards
What are eukaryotic cells?
Have a nucleus which contains the genetic material (DNA)
Animal and plant cell
What are prokaryotic cells?
Don’t have a nucleus
Bacterial cells
Smaller and simpler in comparison to eukaryotic cells
What are the features of all eukaryotic & prokaryotic cells?
- Genetic material (DNA)
- Cell membrane
- Cytoplasm
Describe the genetic material (DNA) in a prokaryotic cell
A single loop of DNA
May also have plasmids - small rings of DNA
Name the 5 sub-cellular structures in animal cells
What is the function of the cytoplasm?
Gel-like substance where chemical reactions take place
What is the function of the nucleus?
Contains the genetic material (DNA)
Controls activities of cell
What is the function of the cell membrane?
Controls movement of substances in and out of cell.
What is the function of the ribosomes?
Where proteins are made
What is the function of the mitochondria?
Where aerobic respiration takes place → releases energy from glucose
Name the additional 3 sub-cellular structures in plant cells
What is the function of the cell wall?
Strengthens the cell
Made of cellulose
What is the function of the chloroplasts?
Contain chlorophyll to absorb light for photosynthesis to make glucose
What is the function of the permanent vacuole?
Contains cell sap
Keeps cell rigid
What is the function of a nerve cell?
Carry electrical impulses
What features of a nerve cell help it carry out its function?
Long → carry electrical impulses over long distances
Many branches → connect to many other cells forming a network
Insulation → speeds up transmission of impulses
What is the function of a sperm cell?
Fertilize an egg
What features of a sperm cell help it carry out its function?
Long tail → allows sperm to swim / move towards egg
Many mitochondria → high rate of respiration to release energy for swimming
What is the function of a red blood cell?
Carry oxygen around the body
What features of a red blood cell help it carry out its function?
Contains haemoglobin → Binds to oxygen
No nucleus → More space for haemoglobin
Biconcave shape → Gives a large surface area for a fast rate of diffusion of oxygen
What is the function of a muscle cell?
Contract to cause movement
What features of a muscle cell help it carry out its function?
Many mitochondria → high rate of respiration to release energy for contraction
What is the function of a root hair cell?
Absorb (take up) water and mineral ions from soil
What features of a root hair cell help it carry out its function?
Long projection → large surface area for absorption of water by osmosis
Many mitochondria → high rate of respiration to release energy for active transport of mineral ions
No chloroplasts → underground → no light / do not carry out photosynthesis
What is the function of the xylem?
Transport water and mineral ions from roots to leaves
What features of a xylem cell help it carry out its function?
Lignin in cell wall → waterproof & strong to withstand pressure of water moving
Hollow cells (no nucleus & sub-cellular structures) → more space for movement of water
No end walls between cells → cells form a long tube so water can flow easily
What is the function of the phloem?
Transports sugars up & down plant
What features of a phloem cell help it carry out its function?
Cells have few sub-cellular structures → more space for movement of dissolved sugars
Pores in end walls → dissolved sugars can move from cell to cell
Name the parts of a light microscope
Describe how to use a microscope to view a prepared slide
- Clip slide on stage and turn on light
- Select lowest power objective lens (usually x 4)
- Use coarse focusing wheel to move stage close to lens
- Turn coarse focusing wheel to move stage away from lens until image comes into focus
- Adjust fine focusing wheel to get a clear image
- Swap to a higher power objective lens, then refocus
When preparing a slide of onion cells why do each of the following steps:
Use a thin layer of onion tissue
Add stain
Lower coverslip at an angle
Thin layer of onion tissue → light can pass through & help see individual cells
Add stain → help see sub-cellular structures
Lower coverslip at an angle → prevent air bubbles
How is the total magnification of a microscope calculated?
Magnification of eyepiece lens x magnification of objective lens e.g. 10 x 4 = x 40
What are the rules of scientific drawing
No colouring / shading – only use clear, continuous lines
Include the magnification
Label important features e.g. nucleus
What is the difference between magnification and resolution?
Magnification = Number of times bigger image is compared to real object
Resolution = Ability to distinguish (tell apart) two points that are close together (level of detail)
What are the differences between light and electron microscopes?
Higher magnification in electron microscopes
Higher resolution in electron microscopes
So can study cells in much finer detail → see more sub-cellular structures e.g. ribosomes
List the steps in calculations involving magnification, real size and image size
- Note formula / rearrange if necessary
- Convert units if necessary – image and actual size must be in the same unit
- Calculate answer and check units required
How do you convert millimetres (mm) into micrometres (µm)
x1000
How do you convert micrometres (mm) into millimetres (µm)
÷1000
An image of an cheek cell measures 40 mm wide. The real width of the cell was 0.01 mm. Calculate the magnification.
- Formula: magnification = image size ÷ real size
- Calculation: magnification = 40 ÷ 0.01 = 400x
An image of an onion cell measures 48 mm long when viewed at a magnification of x400. Calculate the real length of the onion cell. Give your answer in micrometers.
- Formula: real size = image size ÷ magnification
- Calculation: real size = 48 ÷ 400 = 0.12mm
- Convert to required unit: to convert mm to µm x 1000 → 0.12mm x 1000 = 120µm
