Topic 2 - Cells Flashcards
What do eukaryotic cells contain?
-Cell surface membrane
-Nucleus (Including nuclear pores, nuclear envelope, nucleolus, nucleoplasm)
-Mitochondrion
-Cytoplasm
-Rough Endoplasmic reticulum
-Smooth endoplasmic reticulum
-Lysosomes
-Centrioles
-Golgi apparatus (+ vesicles)
What structures are unique to plant cells
-Cell wall
-Vacuole
-Chloroplasts
What are plant cell walls made from
Cellulose
What are bacteria (Prokaryotic) cell walls made from?
Glycoproteins (Murein)
What are fungus cell walls made from
Chitin
What is the function of the nucleus
Stores hereditary information
What is the function of the nuclear pores
Movement of large molecules
What is the function of the nuclear envelope
Controls what exits and enters the nucleus
What is the function of the nucleolus
Produces ribosomes and ribosomal RNA
What is the function of cell surface membrane
Controls what exits and enters the cell
What is the function of the nucleoplasm
Makes up the bulk of the nucleus
What is the function of cytoplasm
Site of chemical reactions
What is the function of the rough endoplasmic reticulum
Produces, stores and transports proteins
What is the function of the smooth endoplasmic reticulum
Produces, stores and transports lipids
What is the function of the golgi apparatus ( + vesicles)
Packages and modifies molecules
What is the structure and function of the mitochondria
Double membrane (cristae and matrix)
Site of aerobic respiration
What is the function of lysosomes
Hydrolyses waste material
What is the structure and function of the chloroplasts
Grana (discs) and stroma (liquid)
Photosynthesis
What is the function of the vacuole
stores unwanted chemicals and maintains the rigidity of the cell
What is the function of centrioles
Produces spindle fibers
What is the structure of a prokaryotic cell
-Capsule
-Cell wall
-Cell surface membrane
-Pilli
-“Naked” DNA
- Plasmids
-Smaller ribosomes
-Chlorophyll
-Flagellum
What is the structure of viruses
-Attachment proteins
-Lipid envelope
-Matrix
-Capsid
-Genetic info (DNA/RNA)
-Reverse transcriptase enzyme
Compare the structure of a eukaryotic and prokaryotic cell
-Linear DNA vs naked DNA
-larger ribosomes vs smaller ribosomes
-mitochondria vs no mitochondria
-none vs capsule
- cellulose vs glycoproteins
How is genetic info stored in eukaryotic cells
Linear DNA which is associated with histones and stored as chromosomes
What are the types of microscopes
-Light/optical
-Scanning electron microscope (SEM)
-Transmission electron microscope (TEM)
How does a SEM work
Electrons are fired at a sample and the electrons reflected back are measured
How does a TEM work
Fires electrons at a sample and measures the electrons which pass though the specimen
How are electron microscopes focused
Using focusing magnets
What are advantages of SEM
High magnification and resolution, produces 3d images
What are disadvantages of SEM
Expensive, cannot be used on live specimens, heavy metal stains used, black and white image
What are disadvantages of TEM
Expensive, cannot be used on live specimens, heavy metal stains used, black and white image
What are advantages of TEM
Very high magnification and resolution, can see organelles
What are advantages of a light microscope
Easy to use, cheap can magnify live samples
What are disadvantages of light microscopes
Relatively low magnification and resolution, cant see organelles
How do you focus a light microscope
Using the fine and coarse focusing wheels
What is the order of magnitude
m, mm, micrometers, nano meters (X1000 going right, /1000 goinjg left)
What are the four stages of mitosis
Prophase, metaphase, anaphase, telophase. (PMAT)
Describe what happens at the metaphase
1.Spindle fibres attach to the centromere
2.Chromosomes align at the equator
Describe what happens in the prophase
1.Chromatin condenses to form chromosomes
2.Centriole attach at the poles
3.Centrioles produce spindle fibres
4.Nucleolus disappears
5.Nuclear envelope disappears
Describe what happens in the telophase
1.Chromosomes are unattached from the spindle fibres
2. Spindle fibres disappear
3. Chromosomes uncoil to form chromatin
4.Nucleolus reappears
5. Nuclear envelope reappears
Describe what happens in the anaphase
- Sister chromatids are split at the centromere by the spindle fibres
- Chromosomes pulled to opposite poles of the cell
What are the 3 stages of the cell cycle
- Interphase
- Mitosis
- Cytokinesis
What is interphase split into
G1, S, G2
What happen in G1
The organelles are duplicated
What happens in S
The chromosome is duplicated
What happens in G2
The cell “double checks” for mutations in the replicated DNA
RP 2 - Garlic root tip experiment
What is the aim of this practical
To investigate mitosis and the mitotic index of a sample
What is the mitotic index
The ratio of cells undergoing mitosis to the total number of cells in the sample
Why is are the roots rinsed with distilled water
To get rid of excess HCl
Why is toluidine blue stain added
To make the chromosomes visible
What is the method for investigating mitosis
- Heat HCl in a water bath at 55 degrees
- Rest the roots of the garlic in the HCl for 5 minutes
3.Rinse excess HCl with distilled water over a beaker - Use filter paper to dry the root tips
- Use a scalpel to cut off the tip of the root
6.Place root tip on the slide and add toluidine blue stain and macerate with a mounted needle - Add a cover slip and using finger pressure press down to break open the cells
- Look for stages of mitosis and record data in order to calculate the mitotic index
Why are the roots dipped in warm HCl
To hydrolyse the glycosidic bonds in the cellulose surrounding the cells
Why is the sample macerated
To get the cells evenly stained and break up the cellulose around it
Why is a mounted needle used to lower the cover slip
To avoid are bubbles from forming
What are the hazards of the mitosis practical
Glassware,working with chemicals, working with scalpels, hot water bath
What are the risks of the mitosis practical
Cuts from broken glass, chemicals on skin or eyes, cutting yourself with scalpel, burns
What are the controls for the mitosis practical
Handle glass with care, wear goggles, use scalpel with care, do not touch hot water bath
What are the actions for the mitosis practical
Do not touch broken glass + tell member of staff, get member of staff to rinse eye using first aid kit, stop bleeding and go to medical room, hold under cold water for 20 minutes minimum.
What five types of molecules make up the cell membrane
-Phospholipids
-glycolipids
-glycoproteins
-proteins
-cholesterol
when in water how does a phospholipid behave
The head will be attracted to the water and the fatty acid tales would be sticking out the water
what does the phospholipid bi layer consist of
A hydrophilic phosphate head and a hydrophobic fatty acid tail
When submerged in water how would the phospholipids behave
They would form a micelle, a 3d structure where all the heads would for a ball like structure and the tails would remain inside
what are glycolipids used for in the cell membrane
cell recognition, receptors
what are glycoproteins used for in cell membranes
cell recognition, receptors
what are proteins used for in cell membranes
Let through larger substances
What are the two types of proteins in the cell membrane
channel and carrier proteins
How do channel proteins work
they form a passage for ions to travel
How do carrier proteins work
They allow larger molecules to diffuse through binding to the complementary receptor which causes a conformational change and pushes the molecules through
what is used in facilliated diffusion
carrier and channel proteins
what type of substances can travel through simple diffusion
small, uncharged molecules such as O2 and C02
Define diffusion
The net movement of molecules form a region of higher concentration t a region of lower concentration until they are evenly distributed
What factors affect diffusion
-Temperature
-Concentration gradient
-Surface Area
-Thickness of the diffusion pathway
Explain how temperature impacts the rate of diffusion
Increased temp means increased KE so more collisions
Explain how concentration gradient impacts the rate of diffusion
Increased concentration gradient so increased molecule to collide
Explain how Surface area impacts the rate of diffusion
Increased SA means increased rate since there Is more spaces for molecules to diffuse
Explain how thickness of diffusion pathway impacts the rate of diffusion
Small diffusion pathway means increased rate since less time taken to diffuse
Define osmosis
The net movement of water from a region of high water potential to a region of lower water potential through a selectively permeable membrane
what is water potnetial
the tendency of water molecules to move
what does a high water potential have
a great proportion of water molecules compared to the solute
what is water potential measured in
KPa
What is active transport?
The movement of ions or molecules in or out of a cell from a region of lower concentration to a region of higher concentration using ATP and carrier proteins
Describe the process of active transport for a Na+ ion
1)Firstly the shape of the Na+ ion is complementary to the receptor on the carrier protein and they bind together
2) Then ATP attaches to the opposite side of the carrier protein
3) As a phophate breaks off the ATP energy is released and consequently ADP and a phosphate are produced
4) The energy released changes the shape f the carrier portion so the ion goes through
5) The shape returns to normal and the ADP and phosphate come back together to form ATP
What is co-transport
The transport of one substance coupled with another through a plasma membrane
What is one example of where co-transport occurs
The ileum of the small intestine
Explain how sodium ions aid the absorption of glucose in the ileum
(First half)
- Sodium ions are actively transported out of the epithelial cell into the capillary
-Therefore there is a greater concentration of sodium in the lumen compared to the epithelial cell
Explain how sodium ions aid the absorption of glucose in the ileum
(Second half)
-Sodium ions under go facilitated diffusion from the lumen to the epithelial cell and simultaneously a glucose is also transported through the use of a co-transport protein
-The glucose can diffuse into the capillary from the epithelial cell through facilitated diffusion
What are the different types of defence mechanisms
Specific and non specific
What is a type of non specific defence
skin and stomach acid
What is a type of specific defence
Lymphocytes
What are the two types go lymphocytes
B and T lymphocytes
What 4 types of non self cells can the immune system identify
Pathogens, non self material from other organisms, toxins, abnormal body cells such as cancer
How many types of lymphocytes are there
10 million
What process occurs when pathogens are engulfed and destroyed
Phagocytosis
Is phagocytosis specific or non specific
Non specific
What is stage 1 of phagocytosis
The phagocyte is attracted to the chemicals secretes by the pathogen (moves towards the pathogen using the concentration gradient)
What is stage 2 of phagocytosis
The phagocyte receptor cells bind to the pathogen
What is stage 3 of phagocytosis
The phagocyte undergoes endocystosis and forms a phagosome
What is stage 4 of phagocytosis
The phagosome fuses with the lysosome and the lysozymes hydrolase the pathogen
What is stage 5 of phagocytosis
The soluble products dissolve into the phagocyte and the antigen is displayed on the surface of the phagocyte
What type of cells are responsible for cell mediated immunity
T cells
Where are t cells produces
bone marrow `
Where do t cells mature
the thymus
What type of cells can t cells work on
body cells only (phagocytes, host body cells, b cells)
Whats the first step of t cell action
Clonal selection
What happens in the clonal selecction of t cells
The t cell with the complementary receptor is identified
What happens in the proliferation of t cells
the chosen t cell is replicated during mitosis
What three types of cells can t cells differentiate into
t memory, t helper, t cytotoxic
What is the role of a t memory cell
secondary immune response
What is the role of a t helper cell
stimulates phagocytosis and b cell proliferation
What is the role of a t cytotoxic cells
destroys infected cells
What types of cells are used in humoral immunity
b cells
what type of cells do b cells interact with
Pathogens
What happens in the clonal selection of b cells
the b cell with the complementary antibody to the antigen of the pathogen is identified
What happens in the proliferation of b cells
the antigen is processed and displayed by the help of t helper cells
What can b cells differentiate into
b memory and b plasma cells
What do b memory cells do
Help with immunity during future infection by producing b plasma cells
What do b plasma cells do
produce antibodies
What 2 regions are found in an antibody
Variable (where the antigen binds) and constant
What two types of chains are found in antibodies
Heavy and light chain
What does the hinge region allow
the binding of more than one antigen at once
What type of bonds are found within the antibody
disulfide bridges
Why are disulfide bridges important in the antibody
They are in the tertiary structure so determine the shape if the protein and make them complementary to a specific antigen
What is agglutination
where multiple antibodies bind to multiple antigens to form a clump
Why is agglutination important
It makes a structure that is too large to enter the cell and makes it easier for phagocytes to engulf and destroy pathogens
What is neutralisation
When an antibody-antigen complex is formed to prevent the cell from entering
What occur when there is a secondary exposure to a pathogen
Antibodies are produced faster and in greater numbers
What is a vaccine
A substance containing one or more antigens of a pathogen to stimulate an immune response
What are the two types of immunity
active and passive
What is passive immunity
Uses only antibodies and is a short term response
What is active immunity
Where the person is exposed to the pathogen or antigen directly (long term response)
What are the two types of active immunity
Natural and artificial
What is natural immunity
when a person is exposed to the pathogen in normal circumstances
What is artificial immunity
The basis of vaccination
What does a successful vaccination programme need
- Economical sustainability
- Little side effects
- means of production and transport
- Means of administration`
What are the ethical implications of vaccination
- use of animals
2.side effects - not everyone wants to be vaccinated
What is herd immunity
Vast majority being vaccinated to reduce the spread of a pathogen
