cell structure Flashcards
Where is the genetic material in a prokaryotic cell?
In a bacterial DNA loop and there may be one or more plasmid rings.
Where is the genetic material in a eukaryotic cell?
The DNA is in chromosomes enclosed in a nucleus.
Why do scientists use prefixes?
To make very small numbers more manageable
sperm functions and features
function is to fertilise an egg.
- streamline with long tail to swim faster
- acrosome in head to digest egg cell membrane
- large number of mitochondria to release energy for swimming
nerve functions and features
function is to carry electric signals
-long to carry signals long distances
-branched connections to connect with other nerve cells and form a network around the body
insulating sheath to enhance transmissions of electric signals
muscle functions and features
function is to contract to allow movement
- contain a large number of mitochondria to release energy from respiration for movement
- long so that there is enough space to contract
root hair functions and features
function is to absorb water and minerals from the soil
-hair like projections to increase the surface area
xylem functions and features
function is to carry water and minerals in plants
- form hollow xylem tubes made of dead tissue
- cells have end plates with holes in them
- glucose in solution moves from leaves to growth and storage tissues in a process called TRANSLOCATION
cytoplasm
where chemical reactions happen
motchondria
most energy is released by respiration here
ribosomes
protein synthesis happens here
vacuole
filled with sap to make cell stronger
plasmid
small ring of dna used in genetic modification
What does cell differentiation mean?
When a cell changes to become specialised.
In what stage of an animal’s life cycle do most cells differentiate?
early stages
In mature animals when do cells still need to differentiate?
for replacement and repair of cells
In what stage of their life cycle do plant cells differentiate?
they differentiate throughout
Define the term resolution.
The shortest distance between two objects that can be seen clearly.
What are the advantages of the electron microscope?
Electron microscopes
have a higher magnification and resolution than light microscopes
Name the smallest cell structures that can be seen by the light microscope?
Nuclei and mitochondria
What are the smallest cell structures that can be seen by the electron
microscope?
internal structures of mitochondria and chloroplasts.
magnification equation
magnification = size of image/size of real object
Describe how you would make an onion cell slide.
-Place thin section of onion epidermis onto slide.
-Place a drop of iodine in the middle of the slide to stain the onion.
-Gently lower cover slip onto the onion without trapping air
bubbles.
-Soak up any excess liquid with a paper towel.
Describe how you would use the light microscope to view onion
cells.
-Switch on the light source and place your slide on the stage.
-Use the lowest objective lens and turn the focusing wheel to move
the lens close to the slide.
-Slowly adjust the focusing wheel until you can see a clear image.
-Increase the magnification by changing the objective lens and re-focus.
