B1a - cell structure and microscopy fact test Flashcards
features of a eukaryotic cell
- have a nucleus
- bigger than prokaryotic cells
features of a prokaryotic cell
- don’t have a nucleus, instead have DNA loops and plasmids (rings of DNA)
- smaller than eukaryotic cells
function of a nucleus
contains genetic material and controls activities of the cell
function of cytoplasm
where most of the chemical reactions happen
function of cell membrane
controls what enters and leaves the cell
function of mitochondria
where most of the reactions of aerobic respiration happen
function of ribosomes
where proteins are made in the cell/site of protein synthesis
function of cell wall (in plants)
- made of cellulose
- rigid to provide structure and protection
- stops cell from bursting if water pressure increases
function of permanent vacuole (in plants)
- contains cell sap
- stores the nutrients of the cell
function of chloroplasts (in plants)
- contains chlorophyll
- absorbs light for photosynthesis
function of DNA loop (in bacteria cells)
contains genetic material
function of plasmids (rings of DNA in bacteria cells)
can move from one bacteria to another
function of flagellum (in bacteria cells)
rotate or move in a whip-like motion to help the cell move
pros of light microscopes
- easy to use
- relatively cheap
- can use live or dead specimen
- can easily use coloured dyes
cons of light microscopes
resolution is limited to 0.2 micrometers meaning you cannot see sub-cellular structures
pros of electron microscopes
has a higher resolution meaning you can see sub-cellular structures
cons of electron microscopes
- takes a long time to prepare specimen
- specimen must be dead
- image is only in black and white
- very expensive
what is an image
the image we see when looking down on the microscope
what is an object
the sample you are looking at
what is resolution
the ability to distinguish objects from each other (how clear the image)
what is magnification
how many times bigger the image is compared to the object
what is the magnification equation
magnification = image size / actual size
how is a sperm cell adapted to its function
- acrosome to break enzymes on outer layer of egg
- nucleus with 1/2 as much genetic material to join with the egg
- lots of mitochondria to release energy to move
- flagellum to help the cell move
how is a nerve cell adapted to its function
- axon carries nerve impulses
- myelin sheath for insulation so impulses can move quicker
- dendrites for connections to other neurons
how is a muscle cell adapted to its function
- mitochondria to transfer energy which is needed to contract and relax
- can store glycogen to be used in respiration
- proteins that contract
how is a root hair cell adapted to its function
- large permanent vacuole to speed up osmosis
- thin walls to not restrict the movement of water
- increased surface are for water to move
- mitochondria to transfer energy for respiration
how is a xylem cell adapted to its function
- cells die and form long hollow tubes to allow water and mineral ions to move easily
- chemical called lignin builds up in spirals, makes the cell very strong to withstand pressure and supports the stem
how is a phloem cell adapted to its function
- cell walls between cells break down to form sieve plates to allow water and dissolved food the move
- sieve plates are accompanied by companion cells which transfer energy to move food up and down
