B1 Cell Biology Flashcards
What is a Prokaryotic Cell?
Small, simple cells which often form single-cellular organisms
(e.g: bacteria)
What is a Eukaryotic Cell?
Complex cells which often form multi cellular life forms
e.g: animals
Describe the Nucleus
Contains the cells genetic material
In which cells can a Nucleus be found?
Any Eukaryotic cell
See Figure 1
In which cells can Cytoplasm be found?
Any cell
See Figure 1/2
In which cells can Cell Membranes be found?
Any Cell
See Figure 1/2
In which cells can Cell Walls be found?
Eukaryotic plant cells and Prokaryotic cells
See Figure 1/2
In which cells can Chloroplasts be found?
Only Eukaryotic plant cells
See Figure 1
In which cells can Ribosomes be found?
Any Eukaryotic cell
See Figure 1
In which cells can Mitochondria be found?
Any Eukaryotic cell
See Figure 1
In which cells can Plasmids be found?
Any Prokaryotic cell
See Figure 2
In which cells can a Vacuole be found?
Eukaryotic plant cells
See Figure 1
Describe the Cytoplasm
Gel like substance where most of the chemical reactions occur.
Describe the Plasmids
Small Rings of DNA
Describe the Vacuole
Contains cell sap to strengthen the cell
Describe the Mitochondria
Powerhouse of the cell
Describe the Ribosomes
Where protein synthesis occurs
Describe the Chloroplasts
Contains chlorophyll - where photosynthesis occurs
Describe the Cell Wall
Made of cellulose - strengthens the cell
Describe the Cell Membrane
Controls what enters and leaves the cell - holds the cell together
What is the difference between a light and an electron microscope?
Light -
Use light and lenses to form an image of a specimen and magnify it
Can see individual cells and large sub-cellular structures
Electron -
Use electrons to form an image
Have higher resolution and magnification
Can see smaller internal structures
How do you calculate magnification?
image size/ real size
What is a slide?
A strip of clear glass or plastic on which a specimen can be mounted before seeing it on a microscope
Which lens should you use first on a light microscope?
The lowest-powered objective lens
What does the coarse adjustment knob on the microscope do?
Moves the stage up and down
What does the fine adjustment knob on the microscope do?
Correct the resolution
What do you change if you want greater magnification on a microscope?
Use a higher-powered objective lens
What is differentiation
A process by which cells change and become specified to their function
Until when can animal cells undergo differentiation?
Lost at an early stage, after becoming specialised
Until when can plant cells undergo differentiation?
Forever
Define Stem Cell
An undifferentiated cell
How is a sperm cell specialised?
Long tail and streamline head to swim to the egg
Many mitochondria for energy
Carries enzymes in the head to digest the egg membrane
How is a nerve cell specialised?
Very long
Branched connectives to connect to other nerve cells and form a network
How is a muscle cell specialised?
Long so that they can contract
Many mitochondria for energy
How is a root hair cell specialised?
Large surface area for absorbing most water and mineral ions
How is a phloem cell specialised?
Few sub cellular structures so that substances can flow through
How is a xylem cell specialised?
No sub cellular structures so that substances can flow through
What is contained by the nucleus?
Genetic Information
What are chromosomes?
Coiled up lengths of DNA
What are genes?
A section of a chromosome which controls a certain characteristic
A single chromosome may contain many
How many chromosomes in most cells?
23 pairs (46 total) (egg and sperm have only 23 chromosomes)
How do body cells reproduce?
Divide
What is the name of the process during which cells are dividing?
Mitosis
What is the name of the time during which cells are not actively dividing?
Interphase
What is Cytokinesis?
The section of mitosis when the cell splits into two daughter cells
What happens in a cell during interphase?
Growing and increasing amount of sub-cellular structures
Create exact copies of all of its chromosomes
What happens in a cell during mitosis?
Half of each chromosome is pulled to either end of the cell
Membranes form around the two new sets of DNA (this is the nucleus)
What happens in a cell during cytokinesis (still also mitosis)?
The cytoplasm and cell membrane divide
They now have two identical daughter cells
What is the process by which prokaryotic cells divide?
Binary Fission
Describe the process of binary fission
Plasmids and circular DNA replicate
Plasmids and circular DNA move to opposite poles
Cytoplasm divides and new cell walls begin to form
Two daughter cells are produced
Are the daughter cells of binary fission identical?
Not always
The have the same circular DNA but may have varying numbers of plasmids
What happens to bacteria cells if under unfavourable conditions?
They die :-(
What do culture mediums contain?
Carbohydrates, Minerals, Protein and Vitamins
What is grown under cultured conditions?
Bacteria and some other microorganisms
Give to examples of cultured mediums
Nutrient broth Solution
Solid agar jelly
What is a colony?
The area bacteria spread to occupy on agar jelly
What is an inhibition zone?
A clear area in which the bacteria have died around an antibiotic/antiseptic
What is contamination?
When unwanted substances come into contact with your experiment
How would you sterilise an inoculating loop?
Flame
Why should petri dishes be stored upside down?
To prevent condensation falling on the agar surface
How do you calculate area of inhibition zones?
Area = πr^2
How could we compare the effectiveness of different antibiotics?
Create agar plates with several examples of different antibiotics (including a control)
Store them for a few days upside down
Measure and calculate the area of inhibition
The greater the area the greater the effectiveness
Where can stem cells be found in humans?
Embryos
Adult Bone Marrow
What cells can embryonic cells differentiate to?
Any human cell
What cells can adult cells differentiate to?
Limited cells for repair of tissues
How can we make stem cells useful?
We can produce clones
What is therapeutic cloning?
Using stem cells from an embryo with the same genetic information as a patient
This prevents rejection from the body
Why must stem cell research follow such strict guidelines?
People feel it is taking away a potential life and thus immoral
What is a Meristem Cell?
An undifferentiated plant cell
Define Diffusion
The movement of particles from an area of high concentration to an area of low concentration
In what states of matter does diffusion occur?
Liquid and Gas
How does concentration gradient affect the speed of diffusion?
The greater the concentration gradient, the greater the rate of diffusion
How does temperature affect the speed of diffusion?
The greater the temperature, the greater the rate of diffusion as particles have more energy
Define Osmosis
The movement of water molecules across a partially permeable membrane from a region of higher concentration to a region of lower concentration
What is a partially permeable membrane?
One with very small holes
Define Active Transport
The movement of substances against the concentration gradient?
Which type of transport requires energy?
Active Transport
What is surface area:volume ratio?
How large the surface area of something isn compared to how big it is overall
Give an example where a plant uses active transport
Root Hair Cells take in minerals from soil despite having more inside than out
Give an example where a human uses active transport
Taking glucose from the gut and from kidney tubules
What happens when there is a lower concentration of nutrients (glucose and amino acids) in the gut than the blood?
Active Transport
How are nutrients in the gut usually transported into the blood?
Diffusion as there is USUALLY a negative concentration gradient
What nutrients are exchanged between the gut and blood?
Amino Acids
Glucose
How are alveoli adapted for maximum diffusion?
Large Surface area (75m^2)
Moist Lining
Thin Walls
Good blood supply
What are the projections in the small intestine called?
Villi
What do the villi do?
Allow digested food to be absorbed more quickly into the bood
How are villi adapted for maximum absorption?
Large Surface Area
Single layer of surface cells
Good blood supply
What substances travel through the stomata?
Oxygen, water vapour out
CO2 in
What is the gas exchange surface on a fish?
Gills
How do fish respire?
Water comes in through the mouth and oxygen in this then diffuses through the gills into the respiratory system
How do gills increase thie surface area?
They have gill filaments (thin plates that make up each gill)
They have lamellae on the filaments which further increase the surgace area
