Topic 1 - Cell biology Flashcards
What are the two types of cells?
prokaryotes and eukaryotes
What is a prokaryote cell?
small simple, single celled organism
What is a eukaryotic cell?
complex and include animal and plant cells
What are the five features in an animal cell?
- nucleus
- cell membrane
- cytoplasm
- mitochondria
- ribosomes
What does the nucleus do?
contains genetic information that controls activity of cell
What does the cell membrane do?
holds cell together and controls what goes in + out.
What does the cytoplasm do?
- gel like substance where most chemical reactions take place
What does the mitochondria do?
most reactions for aerobic respiration take place
What do the ribosomes do?
where proteins are made
What sub cellular structures do plant cells have?>
- cell wall
- permanent vacuole
- chloroplasts
What does the cell wall do?
- made of cellulose
- supports and strengthens cell
What does the permanent vacuole do?
-contains cell sap
what do chloroplasts do?
- photosynthesis occurs which makes food for plants
- contain chlorophyll, which absorb light for photosynthesis
What structures do bacterial cells have?
- cytoplasm
- cell membrane
- cell wall
- plasmids §
How do light microscopes work?
use light and lenses to form an image of a specimen and magnify it
Explain electron microscopes?
use electrons instead of light to form an image
Benefits of electron microscopes?
- higher magnification
- higher resolution
- lets us see smaller things in more detail
define resolution?
ability to distinguish between two points
How do you work out magnification?
image size / real size
Briefly explain how to prepare a slide?
- drop of water onto clean slide
- peel small layer of specimen
- use tweezers to place epidermal tissue into water
- add drop of iodine solution ( stains it)
- place cover slip
What is a slide?
a clear strip of glass or plastic onto which a specimen is mounted
What is differentiation?
process by which a cell changes to become specialised for its job
When does most differentiation occur?
as an organism develops
What are undifferentiated cells?
stem cells
Explain sperm cell specialisation?
- for reproduction ( carry male DNA to female DNA)
- long tail + streamlined head
- lots of mitochondria in cell for energy
- carries enzymes in its head to digest through egg cell membrane
Explain nerve cell specialisation?
- for rapid signally or to carry electrical pulses from one part of body to other
- long to cover more distance
- branched connections at end to connect to other nerve cells and form a network throughout body
Explain muscle cell specialisation?
- contract quickly
- long for space to contract
- contain lots of mitochondria to generate energy for contraction
Explain root hair cell specialisation?
- absorbing water and minerals
- long hairs with big surface area form absorbing water + mineral ions from soil
Phloem + xylem specialisation?
- transporting substances
- long and joined end to end
- xylem are hollow In the centre and phloem cells have very few sub cellular structures so stuff can flow through
What do chromosomes contain?
genetic information
what are chromosomes/
coiled up length of DNA molecules
what do different genes control?
development of different characteristics
How many pairs of chromosomes does a human cell have?
23
What does the cell cycle make new cells for?
growth, development and repair
What is the stage in the cell cycle where cell divides called?
mitosis
What does the end of the cell cycle result in?
- two new cells identical to the original cell, with same number of chromosomes
What are the two stages in the cell cycle/
mitosis, growth and DNA replication
Explain the growth and DNA replication stage?
- cell grows and increases the amount of sub cellular structures such as mitochondria and ribosomes
- duplicates DNA, which is copied to form X shaped chromosomes
Explain the mitosis part of cell cycle?
- chromosomes line up at the centre of cell and cell fibres pull them apart.
- two arms of each chromosome go to opposite end of cell
- membranes form around each of the sets of chromosomes to become nuclei of two new cells
- cytoplasm and cell membrane divide
Explain the result of Mitosis?
two new identical daughter cells
How do prokaryotic cells divide?
replicate by binary fission
Explain binary fission?
- circular DNA and plasmid replicate
- cell gets bigger and circular DNA strands move to opposite poles of cell
- cytoplasm begins to divide, new cell wall begins to form
- cytoplasm divides and two daughter cells are produced - each has one copy of DNA but variable number of plasmids
What are the right conditions for bacteria to divide?
warm, lots of nutrients
How can you grow bacteria?
in a lab with a culture medium
what are the two types of culture medium?
- nutrient broth solution, solid agar jelly
What will bacteria grown on an agar plate form?
visible colonies on the surface of jelly or will spread out to give an even covering
Explain how to make an agar plate?
- hot agar jelly poured into a Petri dish
- when jelly set and cooled, inoculating loop can be used to transfer micro organs to culture medium
What can embryonic stem cells do?
turn into any type of cell
Where can you find stem cells?
early human embryos and adult bone marrow
What can adult bone marrow turn into ?
only turn into blood cells
What are stem cells from bone marrow currently being used to treat?
replace faulty blood cells
what are embryonic stem cells currently being used for?
insulin producing cells for people with diabetes or nerve cells for people with spinal cord injuries
Why are people against stem cell research?
- humans embryos shouldn’t be used for experiments as it is a human life
- researchers should focus on other methods so people can be helped without embryos
What are the advantages of stem cells?
- more important to cure suffering patients then embryos
- usually unwanted anyway as from clinics and would be thrown out
Where are stem cells found in plants?
meristems
How are stem cells useful for plants?
- can produce clones of whole plants quickly and cheaply
- produce clones of rare species
