2 - Cells and Microscopy Flashcards
Nucleus structure
Surrounded by a double membrane nuclear envelope with nuclear pores. Has chromosomes, (protein-bound, linear DNA) and one or more nucleolus
Nucleus function
Nucleolus - site of rRNA product and makes ribosomes. DNA replication and transcription
Cell membrane structre
Phospholipid bilayer
Cell membrane function
Transport, cell recognition, fluidity, receptor
SER structure
No ribosomes. Sheet like membranes linked to nucleus, form cisternae
SER function
Create, store and modify carbohydrates
RER structure
Has ribosomes. Sheet like membranes linked to nucleus, form cisternae
RER function
Site of protein and glycoprotein synthesis.
Cell wall structure (eukaryotic)
Cellulose. Has middle lamella (boundary between two adjacent cells)
Cell wall function
Structural support and prevent bursting when undergoing osmosis
Lysosome function
Contain digestive enzymes which break down material
Ribosome structure
Small granules made of protiens and RNA. 80s and 70s
Ribosome function
Site of translation in protein synthesis
Vacuole structure
Single membrane sac filled with salts, sugars and AA. Has a tonoplast
Vacuole function
Structural support. Store AA and sugars. Pigmented = attract pollinators
Golgi apparatus structure
Stack of cristae
Golgi apparatus function
Modify proteins received from the ER. Add carbohydrates to form glycoproteins. Then transported in vesicles .
Lysosome structure
Formed when GA contains hydrolytic enzymes
What are cristae?
Stacks of membranes creating flattened sacs in GA
What are cisternae?
Network of tubules and flattened sacs. SER and RER
What is a tonoplast?
Membrane around a vacuole
What is a tonoplast?
Membrane around a vacuole
Describe the capsule?
Slime layer outside cell. Stops it from drying out and sticking together
Describe the cell wall (prokaryotic)
Murein
Describe the cell membrane (prokaryotic)
Same to eukaryotic - boundary between inside and outside
Describe the flagellum
Tail that rotates to move
Describe the nucleoid
Single circle of DNA that has genetic materia;
Describe the plasmid
Small loops of DNA that contributes to antibiotic resistance
Describe the mesosome
Inner folding of cell membrane. Large SA for enzymes used in respiration
Describe the ribosomes (prokaryotic)
70s. Not attached to membrane
Describe the ribosomes (prokaryotic)
70s. Not attached to membrane
What is homogenisation?
Break cell wall in blender and filter to remove debris
What is ultracentifugion?
Fractions of filtered homogenate are filtered in tube
3 things the solution needs to be
Buffered, ice cold, isotonic
Why does solution need to be buffered?
pH is constant so enzymes don’t denature
Why does solution need to be ice cold?
Enzymes are slow so don’t destroy organelles
Why does solution need to be isotonic?
Prevents osmosis so organelle can’t burst/shrink
Process of cell fractionation
- Chop up in ice-cold, isotonic and buffered solution
- Filter to remove debris
- Use centrifuging so most dense forms pellet and suspending organelles form supernatant
- Pour into another tube and repeat
Describe the phospholipid bilayer
Hydrophobic fatty acid and hydrophilic phosphate group. :) lipid soluble to enter and prevents water soluble substances to enter or leave
Describe the glycolipid
Maintain stability, cell recognition and attachment
Describe the glycoprotein
Attach to form tissues, cell recognition
Describe the intrinsic protein
Carrier and channel proteins
Ions, AA, sugars pass
Describe the extrinsic protein
Hormone receptor, cell recognition
Describe cholestrol
Control fluidity and prevents water soluble and dissolved ions from leaving
Describe the carbohydrate branch
Nothing
Describe the carbohydrate branch
Nothing
Define diffusion
Net movement of molecules from a high to low concentration down the concentration gradient until evenly distributed
What impacts rate of diffusion?
Size, concentration, distance, temperature, SA
How does size impact rate of diffusion?
Less KE needed at same temp so move quicker
How does concentration impact rate of diffusion?
Bigger conc. gradient = more likely to collide over region
How does distance impact rate of diffusion?
Small = time taken to travel is short
How does temperature impact rate of diffusion?
More KE = move quicker = more likely to collide
How does SA impact rate of diffusion?
More space for diffusion = happen faster = more opportunities for collisions
Define facilitated diffusion
Movement of molecules from a high to low concentration with the use of proteins
What molecules can be transported by diffusion?
Lipid soluble, non-polar, small, O2, C02
What proteins are involved in facilitated diffusion? How?
Carrier - large molecules attach and change shape to pass
Channel - form pores and charges particles
Both hydrophilic
What molecules can be transported by facilitated diffusion?
AA and glucose, water soluble, charged ions
What molecules can be transported by facilitated diffusion?
AA and glucose, water soluble, charged ions
What impacts permeability? (5)
Size, lipid soluble, alcohol conc., electrical charge, SA
What is the unit for pressure?
KSI
Water potential of pure water
0
Define osmosis
Movement of water molecules from a highwater potential to an area of low water potential through a selectively permeable membrane.
Define active transport
Movement of molecules from a high to low concentration by moving against the con. gradient. Involves ATP and carrier proteins
Osmosis pratical
Potato chip
Process of active transport
- Molecule binds to carrier protein at receptor site
- ATP binds to protein at other side which splits (hydrolysis so ADP + phosphate)
- protein changes shape and opens at other side
- molecule released
- ATP reformed and protein reverts to original shape
What impacts rate of active transport? (4)
Number of carrier proteins, carrier protein speed, rate of respiration
Small protein adaptations (4)
Big SA, villi, thin epithelial layer, good blood supply
Ions involved in co-transport
Na+ and K+
Process of co-transport
- C6H12O6and Na+ into epithelial cells (co-trans)
- Na+ into blood from epithelial cells and K+ into epithelial cells from blood (act.tra)
- C6H12O6 from epithelial cells to blood (f.diffusion)
T-cell response name
Cell mediated
B-cell response name
Humoral
Two types of defence and examples
Specific - T and B cells
Non-specific - phagocytosis, physical barrier
3 ways how lymphocytes recognise body cells
Foetus (collide w other cells)
Lymph. collide with own material
Survive if receptors for with foreign antigen
What is a macrophage?
APC that is a WBC
What are the 2 types of phagocyte
Neutrophil and monocyte
What is a neutrophil?
Phagocyte - short life span, arrive first and die after engulfing
What is a monocyte?
Phagocyte - mature to macrophage before engulfing
Describe process of phagocytosis
- Pathogen in blood stream and phagocyte recognises foreign antigens
- Receptors bind and engulf
- Pathogen enclosed in a phagosome
- Phagosome and lysosome fuse
- Empty contents into phagosome (hydrolytic enzymes)
- Pathogen destroyed and exocytosis happens
4 ways how phagocytes are specialised and description
Cytoskeleton - change shape to engulf pathogen and move lysosomes
Mitochondria - cell movement and phagocytosis need energy
Ribosomes - Protein synthesis (lysosome enzymes)
Lobed nucleus - enter narrow gaps and change shape
Types of T-cells and description
Cytotoxic - destroy antigen
Helper 1 - stimulate phagocytosis
Helper 2 - stimulate B-cell production
Memory - remember antigen
How T cells work
Phagocytosis - WBC presents antigen - fuse with T cells - mitosis
What do B cells undergo?
Clonal expansion
Process of B cell production
Phagocyte becomes APC - present antigen to B cell - antigen is complementary to receptor - B cell presents antigen - bind and activate - T-helper cells bind and secrete cytotoxins which stimulates mitosis
Types of B cells and description
Plasma - secrete antibodies and primary immune response
Memory - if encounter same antigen, divide rapidly to make plasma cells. Secondary response
Label an antibody
Light chain - not attached bit Heavy chain - connected bit Variable region - top half Constant region - bottom half Antigen binding site - top Receptor binding site - bottom
Bond in an antigen
Disulphide bond
Antigen bonding to binding site forms a ….
Antigen - antibody complex
4 functions of antibodies
Agglutination, opsonisation, antitoxins, lysis
Describe agglutinstion
Pathogens are clumeped together
Describe oposonisation
Pathogens are coated with antibodies
Describe antitoxins
Toxins produced by pathogen are neutralised
Describe lysis
Bacteria are destroyed by digestion and rupture bacteria membrane
Name the 3 types of immunity
Herd, active, passive
Describe herd immunity
Protection by a viral percentage of population by being vaccinated
Describe active immunity
Ability to produce own antibodies
Describe passive immunity
Just receive the antibodies
Two methods to get active immunity
Natural - after infection
Artificial - Vaccination
Two methods to get passive immunity
Injection following infection and antibody from mother to foetus
4 ways a vaccination program is successful
Economical
Few side effects
Stable and easy to store
Easy to administer
3 ways a vaccination program is unsuccessful
Pathogen frequently mutates
Pathogen hides from immune system
People refuse to be vaccinated
Process of being immune by vaccination
- Pathogen enters body and T/plasma cells made
- B and T cells differentiate
* first exposure and primary response 10-17 days* - Become ill due to slow process
* Secondary response* - Second exposure to same antigen (2-7 days and higher magnitude/prolonged)
- Happens due immunological memory
Difference between HIV and AIDS
HIV = pathogen AIDS = Disease
How is HIV transmitted?
unprotected sex, birth, sharing needles
How does HIV impact the body?
Destroy T cells so weak immune response (supressed)
Define opportunistic infections
Not likely to impact healthy people but causes harm if immune system is supressed
Signs and symptoms of AIDS
- Acute infection - divide rapidly and seed in body (no
symptoms and inactive) - 2-4 weeks later, flu like symptoms and swollen lymph glands
What is the ELISA test?
Detect small quantities of proteins (antigens)
Name 6 things found in HIV
Lipid envelope, matrix, RNA strands, glycoprotein, capsid, reverse transcriptase
What is a lipid envelope? (HIV)
Lipid bilayer that surrounds virus. Allows to fuse with other membranes
What is a matrix? (HIV)
Protein layer
Structural support
What is a glycoprotein? (HIV)
Bind with CD4 on T helper cells - surface protein
What is a capsid? (HIV)
Protein coat - genetic material and some enzymes
What are RNA strands? (HIV)
2 - contain al genetic material
What is reverse transcriptase? (HIV)
Enzymes that catalyse synthesis of rna -> dna
3 uses of monoclonal antibodies
Pregnancy test, cancer, medical diagnosis
How are monoclonal antibodies used in pregnancy tests?
HCG produced by placenta binds to MCA and move along strip
How are monoclonal antibodies used in cancer treatment?
Block chemical signals for growth
How are monoclonal antibodies used in medical diagnosis’s?
Obtain sample of blood and detect quantity of a substance
3 reasons why monoclonal antibodies arent ethical
Involve mice
Caused some deaths
Testing has dangers
Name 3 types of microscope
SEM, TEM OLM (optical light)
3 pros of SEM
3D
See internal structures
Still fairly high resolution
3 cons of SEM
Vacuum needed
Staining process
Lower resolution
3 pros of TEM
Highest resolution - short wave length
Chemical analysis
3 cons of TEM
2D
Sample destroyed by e-
Need staining process
3 pros of light microscope
Cheap
Colour
Portable
1 con of light microscope
Low resolution - long wavelength
Why does the nucleus form at the bottom of the test tube in centrifuging?
It’s the most dense
When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how.
- Vaccine contains antigen from pathogen
- Macrophage presents antigen on its surface
- T cell with complementary receptor protein binds to antigen
- T cell stimulates B cell
- With complementary antibody on its surface
- B cell secretes large amounts of antibody
- B cell divides to form clone all producing same antibody
