B1: Cell Structure and transport and microscopy Flashcards
Describe magnification
Magnification is how much bigger the image you see is, than the actual specimen itself
Describe resolution
Resolution is the smallest distance you can see between two separate points.
what are the advantages of using a light microscope (3)
- They use a beam of light to form an image so therefore it can be used almost anywhere
- The best light microscopes can magnify things up to 2,000 times larger.
- small and cheap
what are the disadvantages of using a light microscope
- cannot resolve distances smaller than 200nm (the size of a visible light wave)
what are the advantages of using an electron microscope (3)
- They are used to study the inside of the cells
-they use a beam of electrons to form an image - They can magnify objects up to 2,000,000 times larger
What are the disadvantages of using an electron microscope
- They are large and expensive
- ## They have to be kept in special rooms to control the temperature, pressure and humidity
magnification formula
magnification = size of image/size of real object
Cell membrane function
Controls what goes in and out of the cell
Nucleus function
Contains the cell’s genetic material (DNA) which controls the cells activity
Mitochondria function
powerhouse of the cell, where aerobic respiration occurs, releasing energy
Cytoplasm function
where chemical reactions happen, contains enzymes
Ribosome function
Makes proteins
Vacuole function
stores food, nutrients and waste products
Cell wall function
provides strength and structure, protects the the cell
Chloroplast function
Where photosynthesis takes place
Large central vacuole function
stores water, pigment and toxic materials
what are the differences between an animal cell and a plant cell (4)
- Plant cells have cell walls, animal cells only have a cell membrane
- Plant cells contain chloroplast, animals cells don’t
- Plant cells have vacuoles, animals cells don’t
- plants cells have a rectangular shape while animal cells have a circular shape
Compare prokaryotic cells and eukaryotic cells
- Prokaryotic cells don’t have a true nucleus;
eukaryotic cells do - Prokaryotic cells lack membrane-bound
organelles; eukaryotic cells have them - Prokaryotic cells are smaller; eukaryotic
cells are larger - Prokaryotic cells are simpler; eukaryotic
cells are more complex
Genetic material (prokaryotic cell)
Contains DNA
Plasmids (prokaryotic cell)
Replicate and move between cells so that genetic information can be shared.
Flagella (prokaryotic cell)
Rotate or move in a whip-like motion to move the bacterium.
Pilli (prokaryotic)
Adherence to surfaces, which facilitates infection, and is a key virulence characteristic
Why do animals have specialised cells?
To carry out a particular role in the body
Red blood cell function
To carry oxygen around the body
Nerve cell function
Help contraction of muscles or the relaxation of muscles
Prokaryotic cells
Bacteria cells
Do NOT have nucleus or mitochondria
Eukaryotic cells
Plant and animal cells (and fungi) are all eukaryotic cells, they have a nucleus (and other organelles e.g. mitochondria)
Compare the structure of a specialised and generalised animal cell
- Generalised cells have a simple structure
and can perform basic functions. - Specialised cells have a more complex
structure and are adapted to perform
specific functions within the body.
How are blood cells adapted
- contains haemoglobin (red pigment which binds to oxygen
- biconcave disks fro increased surface area for diffusion
- No nucleus for more space for haemoglobin
What is the percentage composition of the red blood cell
40-45%
how are sperm cells adapted
- A tail to move them towards an egg cell.
- Many mitochondria to provide energy.
- nucleus carries half the amount of genetic material as a normal adult cell
Define specialised cells
Cells which have a key role in the body/plant by having a specific cell/structure
Define differentiation
The process by which a cell changes to become specialised
Describe diffusion
The net movement of particles from an area of higher concentration to an area of low concentration
Define osmosis
Osmosis is the net movement of water molecules across a permeable membrane from an area of higher water concentration to an area of lower water concentration
Area to volume ration
As the organism gets larger
Surface area : volume ration decreases
