Topic 1 Flashcards
(41 cards)
What is a cell?
The smallest unit of life that can replicate independently
How do bacteria reproduce?
Asexually.
What are the similarities and differences in organelles in plant and animal cells.
Both contain cell membrane - Controls which substances come in and out of the cell.
Both contain nucleus containing genetic material / DNA.
Both contain cytoplasm - Where chemical reactions take place.
Both contain mitochondria - Where aerobic respiration occurs.
Both contain many ribosomes - Where protein synthesis occurs.
Plant cells contain a Cellulose cell wall which provides support and structure.
Plant cells contain a vacuole - Contains cell sap.
Plant cells contain chloroplasts - Where photosynthesis occurs.
What is the structure of a bacteria?
They are unicellular 1 cell.
Bacteria contain Cell membrane, Cell Wall, Ribosomes and cytoplasm.
They have a single circular strand of DNA that floats around the cytoplasm.
Some bacteria also contains plasmids extra genes.
Some also contain Flagella which allow the bacteria to move around.
What is the equation to find the Actual image size?
Image / magnification = Actual size
What are the advantages and disadvantages of light microscopes?
Easy to use
Relatively cheap
In colour
Does not have a very good resolution.
What are the advantages of electron microscopes?
Advantages = High magnification
better resolution so clearer image so you can see subcellular structures clearly.
Disadvantages - Hard to use and expensive and in black and white.
Label all the parts of the light microscope.
What are the 3 stages of cell division mitosis?
1) Interphase - Cell grows in size increases number of sub-cellular structures such as mitochondria and ribosomes.
2) Next the chromosomes are replicated to double the amount of genetic material in a nucleus and appear as X shape.
3) The chromosomes line up at the centre of the cell and one half of each are pulled apart to the poles of the cell.
4) Cytoplasm, nucleus and membranes divide resulting in two genetically identical diploid cells daughter cells.
Why is mitosis important in multicellular organism?
Allows growth
Allows repair of tissues
Asexual reproduction
What is binary fission?
The process of where prokaryotic organisms, like bacteria divide and reproduce.
What are the two things that must happen before a bacterial cell can divide?
Replicate Genetic material - so large circular strand of DNA and all the small plasmids.
Once this is done the two large circular strands go to either side of the cell.
However the plasmids are arranged randomly so one might get more than the other.
Then a new cell wall starts to grow in the centre of the cell creating two new bacterial cells.
A bacterial cell has a mean division time of 30 minutes how many cells would it produce after 3 hours.
64
What does the mean division time depend on?
The species of bacteria and the conditions they are in.
For optimum growth you need somewhere warm, moist, oxygen and plenty of nutrients.
A petri dish contains 1000 bacteria. Each cell divides once every 20 minutes how many cells will there be after 4 hours.
4,096,000
What are the Aseptic techniques used to prevent contamination when culturing bacteria.
Sterilize all equipment
Inoculating loop through flame - kills microorganisms.
Sterilise petri dish.
Minimise lid opening - Only partially lift the petri dish lid when adding bacteria and do it quickly to avoid airborne contamination.
Sterilise work surface - Wipe bench down with disinfectant before and after.
Use adhesive tape to tape the lid of the petri dish still allow oxygen in.
Incubate at 25 degrees to prevent formation of harmful pathogens.
What is the method when culturing bacteria?
Sterilise Petri dish and agar jelly using an autoclave.
Pour agar into dish and let it set.
Sterilise inoculating loop in a Bunsen flame.
Dip loop in bacterial culture and spread on agar.
Place antibiotic-soaked paper discs on agar using forceps.
Lightly tape the lid with 2 pieces of tape allow oxygen in.
Flip the petri dish to prevent condensation from the lid dripping onto the agar dish.
Label the dish and incubate at 25°C for 48 hours.
What are the 2 key features of stem cells?
Divide by mitosis to form more cells.
Stem cells are able to differentiate into specialised cells.
What are embryonic stem cells?
Found in early human embryos can differentiate into any type of cell.
What are adult stem cells and where are they found?
Adult stem cells found in few places such as bone marrow. Adult stem cells are unable to differentiate into all types of cells only different types of blood cells.
Where are plant stem cells found?
Found in the meristem of the plant in the roots and the shoots (areas where are continually growing.)
What do plant stem cells do?
Differentiate into all the types of plant cells and tissues the plant needs such as phloem and xylem cells.
Define differentiation.
The process by which a cell changes to become specialised to it’s job.
What are sperm cells specialised for and what are their adaptations?
Sperm cells are specialised for reproduction.
It has a long tail and a streamlined head to help it wim to the egg. The cell contains lots of mitochondria to allow it to provide it with the energy it needs. Contains enzymes in the head to digest through the egg cell membrane.
