Cell Biology Flashcards
what is a eukaryote?
organism with cells that have a nucleus and membrane-bound organelles
is a prokaryotic or eukaryotic cell bigger?
eukaryotic - measured in micrometres (prokaryotic 1/10 smaller, nanometres)
what is the structure of a prokaryotic cell?
cytoplasm, cell membrane, cell wall, genetic material in a single DNA loop in cytoplasm, may be smaller rings of DNA in cytoplasm (plasmids)
what is a prokaryotic cell?
simple cell without a nucleus
what is a pathogen?
microorganism which can cause disease
what are the 6 groups of microorganism?
bacteria, fungi, protozoa, algae, archaea, viruses
describe the structure of an animal cell.
- eukaryotic
- nucleus, mitochondria, ribosomes, cytoplasm, cell membrane
describe the structure of a plant cell.
- eukaryotic
- nucleus, mitochondria, ribosomes, cytoplasm, cell membrane, permanent vacuole, cell wall
what is the function of the nucleus?
contains genetic material
what is the function of the mitochrondria?
releases energy via respiration
what is the function of ribosomes?
carry out protein synthesis
what is the function of the cytoplasm?
most chemical reactions occur here
what is the function of the cell membrane?
controls movement of substances in and out of cell
what is the function of the cell wall?
gives strength to the cell and supports the plant
what is the function of chloroplasts?
absorb light for photosynthesis
what is the function of the permanent vacuole?
filled with cell sap to help keep cell turgid
what is specialisation?
adaptation of an organ or part to serve a special function
give an example of a specialised cell [6].
sperm cells, nerve cells, muscle cells, root hair cells, xylem cells, phloem cells
how are sperm cells specialised?
- have a tail for swimming
- full of mitochondria to provide energy
- acrosome contains enzymes to help break into ovum
how are muscle cells specialised?
- full of mitochondria to provide energy
- contain filaments of protein that slide over each other to cause muscle contraction
what is differentiation?
the process by which cells become specialized to perform specific functions in an organism
what is a stem cell?
an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type and from which certain other cells can arise from differentiation
how do light microscopes work?
use light to view specimens
what is the magnification of a light microscope?
low magnification - x1500
what is the resolution of a light microscope?
low resolution - 200nm
what is a limitation of a light microscope?
details in sub-cellular structures cannot be easily seen
how do electron microscopes work?
use electrons to see surface of cells, or inside of cells; sub-cellular structures can be seen in detail
what is the magnification of a electron microscope?
very high magnification - x500,000
what is the resolution of a electron microscope?
very high resolution - 0.1nm
what is the calculation for magnification?
size of image divided by size of real object
How would onion cells look different if they were seen using an electron microscope rather than a light microscope?
The cells would look larger and would show more internal structures.
how do you set up a light microscope?
- place specimen on stage
- switch microscope on so that light passes through the specimen
- make sure the x4 objective lens is clicked into place above the specimen
- bring specimen into focus by looking down eyepiece lens and moving into coarse focus
- when specimen is in focus, move objective lenses so that the x10 objective lens is clicked into place above specimen
- if specimen is out of focus, bring it into focus using small movements of the fine focus
-7.repeat 5 & 6 with x40 objective lens
Plan an investigation to test effect of antibiotics on growth of bacteria.
- use aseptic techniques to spread bacteria onto agar plate
- grow at 25 degrees for several days, until bacterial colonies can be clearly seen
- place drop of antibiotic solution onto different areas of agar plate and leave for 24 hours
- observe and measure any zones of inhibition
give an example of an aseptic technique [4].
- sterilising all petri dishes and culture media
- sterilising inoculation loops by passing them through a flame
- securing the lid of the petri dish with tape and storing it upside down
- not incubating bacterial cultures about 25 degrees centigrade
what is the purpose of aseptic techniques?
to prevent contamination to test effectiveness of disinfectants and antibiotics
what are 3 types of stem cell?
adult, embryonic, meristem
where are embryonic stem cells found?
embryos (IVF, abortion), umbilical cord
what is a positive of using embryonic stem cells? [2]
can differentiate into any type of human cell to make different organs needed in humans - pluripotent
- create large numbers as easily grown in culture
where are adult stem cells found?
bone marrow
what is a limitation of using adult stem cells? [3]
- limited as to what they can become - rbc (rbc cant be made via mitosis), wbc (in case of infection)
- rare in mature tissues
- methods for expansion not yet worked out
What is meristem tissue?
plant stem cells found at ends of roots and shoots
why do plants have meristem?
stem cells are kept forever because plants dont have all their organs at the start of their life
what are some risks of using stem cells in treatments?
- rejection - immunosuppressants
- infection and anaesthesia
what is a con of using embryonic stem cells? [2]
- probably rejection as not patient’s own dna
- ethical issues as from aborted embryos or spare IVF
what is a pro of using adult stem cells? [2]
- no risk of rejection as dna from patients own body
- no ethical issues
describe the process of therapeutic cloning
- nucleus is removed from human egg cell from donor
- nucleus is removed from patient’s cell and transferred to donor egg cell
- cell is stimulated to divide
- cell develops into embryo
- after 4-5 days stem cells are removed
- stem cells are cultured for therapeutic uses (eg grow organs for transplant)
describe the process of growing plantlets from plant stem cells.
- scrape tissue sample from plant
- tissue sample placed in agar growth medium containing nutrients and auxins
- samples develop into tiny plantlets
- plantlets planted into compost
why are plants are cloned using meristem cells?
- to produce identical plants quickly and economically
- faster than allowing plants to reproduce naturally
- can cultivate desired characteristics ie disease resistance, large and lots of fruit
what is mitosis?
process of cell division were one cell divides into 2 identical daughter cells
what is interphase?
the phase of the cell cycle in which a typical cell spends most of its life-metabolic phase of the cell
- the cell obtains nutrients and metabolizes them, grows, replicates its DNA in preparation for mitosis, and conducts other “normal” cell functions