Section 2: Cells Flashcards
How would i get an organelle out of a sample to study
Cell fractionation : break up cells in a cold buffer isotonic solution
Homogenisation: Cells broken up in homogeniser to release organelles the resultant fluid is the homogenate and debris filtered out
Ultracentrifugation: spins the homogenate in centrifuge heaviest organelle forced to bottom to form pellet and supernatant at top spinner high speed until organelle u want
What’s the equation for magnification
Magnification = image size divided by actual size
Why do we place cells in cold buffer and isotonic solution
cold ( reduced enzyme activity )
buffer ( so ph doesnt change )
isotonic ( same water potential )
all avoid cell movement or change within the cells from sample
Compare TEM and SEM
Feature, TEM, SEM
Image type, 2D (internal structure), 3D (surface details)
Resolution, Higher (up to 0.1nm), Lower (1-20nm)
Magnification, Up to ×500,000, Up to ×100,000
Specimen prep, Thin and complex prep, Less thin but complex prep
Living specimen, No, No
Which electron microscope has a high resolution and magnification
TEM
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What is the function of the cell membrane?
To regulate the entry and exit of substances.
What is a function of the smooth endoplasmic reticulum?
Lipid synthesis.
What is the primary function of lysosomes?
To digest waste materials and cellular debris.
Fill in the blank: The ______ is a rigid layer that provides support and protection in plant cells.
cell wall.
What is the role of the Golgi apparatus?
To modify, sort, and package proteins and lipids.
Which type of cell division results in two identical daughter cells?
Mitosis.
What is the function of the cytoskeleton?
To provide structural support and shape to the cell.
True or False: All cells contain DNA.
True.
Fill in the blank: The process by which cells convert glucose into energy is called ______.
cellular respiration.
What is osmosis?
The diffusion of water across a selectively permeable membrane.
True or False: The rough endoplasmic reticulum is studded with ribosomes.
True.
Fill in the blank: ______ are specialized structures within a cell that perform distinct processes.
Organelles.
What is the difference between active and passive transport?
Active transport requires energy, while passive transport does not.
Multiple Choice: Which structure is selectively permeable? A) Cell wall B) Cell membrane C) Cytoplasm
B) Cell membrane.
What is the primary purpose of mitosis?
To ensure equal distribution of genetic material to daughter cells.
True or False: Eukaryotic cells are generally larger than prokaryotic cells.
True.
Fill in the blank: The ______ is a network of protein filaments that helps the cell maintain its shape.
cytoskeleton.
What is the function of the nucleolus?
To produce ribosomal RNA (rRNA).
What process do cells use to engulf large particles?
Phagocytosis.
Fill in the blank: The ______ is the jelly-like substance within the cell.
cytoplasm.
What structure is responsible for packaging and transporting proteins?
Golgi apparatus.
Multiple Choice: Which type of cell division results in genetic diversity? A) Mitosis B) Meiosis C) Binary fission
B) Meiosis.
What is the role of the plasma membrane?
To protect the cell and control what enters and exits.
True or False: Ribosomes can be found free-floating in the cytoplasm.
True.
Fill in the blank: ______ are membrane-bound organelles that contain enzymes for breaking down waste.
Lysosomes.
What is the main function of the rough endoplasmic reticulum?
To synthesize proteins.
What is the function of vacuoles in plant cells?
To store substances and maintain turgor pressure.
what are the tree main stages of the cell cycle
Interphase
Nuclear division
Cytokinesis
What is cancer
Uncontrolled growth and division of cells
Mutation results in uncontrolled mitosis
What are two treatments of cancer
Prevent DNA replication
Inhibit metaphase part of mitosis by interfering with spindle formation
List the basic structure of the plasma membrane
Phospholipid lipids
Proteins = chanel and carrier proteins
Cholesterol
Glycolipds
Glycoproteins
List the basic structure of the plasma membrane
Phospholipid lipids
Proteins = chanel and carrier proteins
Cholesterol
Glycolipds
Glycoproteins
State the role of phospholipids in the plasma membrane
Allow lipid-soluble substances to enter and leave the cell
Prevent water-soluble substances entering and leaving the cell
make the membrane flexible and self-sealing
What is the function of proteins in the membrane
- Provide structural support
- Act as Chanels transporting water soluble substances
- Allow active transport across the membrane through carrier proteins
- form cell-surface receptors for identifying cells
- help cells adhere together
- act as receptors for example hormones
What is the role of cholesterol in the membrane
- reduce lateral movement
- make membrane less fluid at higher temperatures
- prevent leakage of water and dissolved ions from the cell
What’s the role of glycoproteins in the cell membrane
act as recognition sites
help attach to one other to from tissue
Allow cells to recognise one another ei lymphocytes
What’s the role of glycoproteins in the cell membrane
act as recognition sites
help attach to one other to from tissue
Allow cells to reg lose one another lymphocytes
Why is the cell membrane called the fluid mosaic model
fluid: flexible structure
Mosaic = proteins embedded in the bi layer have varying shapes and sizes
What features would mean a molecule cannot freely diffuse across the membrane
- polar
- not lipid soluble
3.too large - same charge as the protein chanel’s
What is facilitated diffusion
Passive process doesnt require ATP from respiration only the kinetic energy of particles
Uses protein channels and carrier proteins
Describe and distinguish the different roles of carrier proteins and protein channels
Protein chanel’s are water-filled hydrophilic chanel’s and allow water soluble ions pass through. they are selective and only open for specific ions. The ion binds to the protein and causes it to change shape in a way that closes it on one side and opens of the other can be used for facilitated diffusion
Carrier proteins bind to ion and cause it to change shape in a way that the molecule is released to the inside of the membrane can be used for facilitated diffusion and active transport
What is water potential
Water potential is the pressure created by water molecules units kPa
the addition of a solute to pure water will lower the water potential
water potential always negative
pure water has a water potential of 0
How does Active transport differ from passive forms of transport
Metabolic energy in the form of ATP is needed
Substances moved against a concentration gradient
Carrier proteins which act as pumps are involved in
The process is very selective
Describe active transport of a single molecule or ion
Molecule or ion bind to receptor site on a carrier protein
On the inside of the cell ATP binds to the protein causing it to split into ADP and a phosphate
The protein molecule changes shape and opens to the opposite side of the
The molecule or ion is released
The phosphate molecule is released with causes the protein to revert back to shape
The phosphate recombines with ADP to from ATP during respiration
Describe the sodium potassium pump
Sodium ions are actively transported out of epithelial cells by the sodium potassium pump and carrier protien
This maintains a much higher concentration of sodium ions in the lumen of the intestine than inside the epithelial cells
Sodium ions diffused into the epithelial cells down this concentration gradient through a different type of protien carrier in the cell-surface membrane. As the sodium ions diffuse in through this second carrier proteins, they carry either amino acid molecules or glucose molecules into the cell with them
The glucose/amino acids pass into the blood plasma by facilitated diffusion using another type of carrier
What are the two types of lymphocytes (white blood cells) and what are the brief functions
Cell-mediated responses involve T lymphocytes
HUmoral responses involve B lymphocytes
How do lymphocytes recognise cells belonging to the body
Lymphocytes constantly colliding
Some lymphocytes have receptors that exactly fit those of the body’s own cells : these lymphocytes die or are suppressed
The remaining lymphocytes are those that might fit foreign material
What are the 2 types of white blood cells
Phagocytes non-specific
lymphocytes specific
Describe a phagocyte in action
The phagocyte is attracted to chemicals released by the pathogen
Receptors on the phagocyte attach to chemicals on the pathogen
Phagocyte engulfs pathogen to form a phagosome
Lysosomes within the phagocyte migrate towards the bacterium
Lysosomes release lysozymes to hydrolyse the bacterium
The hydrolysis products of the bacterium are absorbed by the phagocyte
What is cell mediated immunity
When T cells respond to antigens that are presented on a body cell / recognise and eliminate infected cells
Please summarise the stages in response of a T lymphocytes to infection of a pathogen
Pathogen invades body cell
The phagocyte places antigen from pathogen on cell surface membrane
Receptors on specific helper T cell fit exactly on to these antigens
This attachment activates the Tcell to divide rapidly by mitosis and form a clone of genetically identical cells
The clones T cells:
develop into memory cells
stimulate phagocytes to engulf pathogens
stimulate b cells to divide and secrete their antibodies
activate cytotoxic T cells
What do the cloned T cells do
The clones T cells:
develop into memory cells
stimulate phagocytes to engulf pathogens
stimulate b cells to divide and secrete their antibodies
activate cytotocic T cells
How do cytotoxic T cells kill infected cells
produce a protein called perforin that makes holes in cell-surface membrane which means membrane becomes freely permeable and cells dies
Describe the role of B cells in immunity
The surface antigens of an invading pathogen are taken up by a B cell
The B cell processes the antigens and presents them on its surface
Helper T cells (activated by T cell process) attach to the processed antigen and activate it
The b cell now activated divides by mitosis to give a clone of plasma cells
The cloned plasma cells produce and secrete the specific antibody’s that fit pathogens antigen
The antibody attached to antigen on pathogen and destroys them
Some B cells develop into memory cells
Contrast the cell mediated and humoral responses to a pathogen
Cell-mediated response involves T cells ( Helper T cells and Cytotoxic cells) and Humoural response involves B cells (Plasma cells and Memory B cells)
Cell-mediated response targets pathogens inside cells humoural immunity targets outside of cells pathogens
Cell-mediated response antibodies aren’t involved Humoural they are
Cell-mediated response time is slow because it requires activation to T cell while humoural response faster as involves production of antibodies
Cell mediated response directly kills infected cells
Both produce memory cells
How does the antigen enter the B cell
endocytosis
What is an antigen
A substance that triggers an immune response, typically by stimulating the production of antibodies or activating T cells
Activated B cells divide into two things…
B memory cells and plasma cells
Why may someone have measles only once and influenza several times
Measles only have 1 antigen type memory cell therefore effective
Influenza have several
antigen variability
Explain the role of macrophages in stimulating B lymphocytes
Present pathogen antigen on cell-surface membrane
What organelles do B lymphocytes need more of and why
Mitochondria provide ATP
ReR and ribosomes synthesise proteins
Golgi body secretes and modify proteins
Lymphocytes produce antibody’s
Why does antibodies passed to fetus only provide short term immunity
Maternal antibodies have antigens with are destroyed by fetal antibodies
What is a pathogen
A microorganisms which causes disease
Describe how antibodies are produced in the body following a viral infection
Virus contains antigens
Phagocytosis
Phagocyte presents antigens on cell-surface membrane
B cells activated
Form clones by mitosis which produce plasma cells or b memory cells
Plasma cells produce antibodies
antibodies attach to antigen and destroy it
Explain an advantage of using antibodies from plants to treat a disease rather than antibodies produce in an experimental animal
Fewer ethical difficulties
or
less risk of infection
Describe one way bacteria might produce symptoms of disease
Releases toxins
damages cells carrying out metabolic functions
What is a monoclonal antibody
An antibody produced by a single clone of identical B cells which are all specific to the same antigen
How do antibody’s cause the destruction of an antigen
agglutination of bacteria cells ( clump them together to make it easier for phagocytes )
serve as markers that stimulate phagocytosis
What is vaccination
An attenuated pathogen injected to produce an immune response activating b-cells producing antibody’s (plasma cells) and b-memory cells
Why are some antibodies referred to as monoclonal
produced from single b-cell clones
Describe the four types of immunity
Passive immunity = introduction of antibodies from an outside source ( anti venom or maternal antibodies )
Active immunity = produced by stimulating the production of antibodies by someone’s own immune system 2 types of this immunity include:
Natural active = natural contact with disease
artificial active = vaxcination no symptoms of disease
Why may vacinations fail to eliminate disease
people with defective immune systems
may develop disease immediately after vaccination before immunity levels develop
Pathogen may mutate frequently causing antigenic variability
individuals may object to vaccine for religious ethical or medical reasons
Describe the replication of HIV
binds to protein called CD4 on T helper cells
The protein capsid fuses with the cell-surface membrane. The rna and enzymes of HIV enter the T helper cell
HIV reverse transcriptase convers viruses RNA into DNA
the new DNA moves into the T helper cells nucleus
The HIV DNA produces messenger RNA to make new viral proteins
The mrna moves out nucleus through nuclear pore to ribosome to use cell synthesis mechanisms to make HIV particles
How does HIV produce the symptoms of aids
Kills T helper cells
which then dont stimulate B cells
Why is HIV called a retrovirus
ability to make DNA from RNA
Why are antibiotics ineffective against viral diseases like AIDS
Viruses within an organisms cell
Why are antibiotics ineffective against viral diseases like AIDS
Viruses within an organisms cell
Function of golgi apparatus
add carbohydrates to proteins to from glycoproteins
produce secretory enzymes
secrete carbohydrates
transport, modify and store lipids
from lysosomes
Where are 70s ribosomes found
70s in prokaryotic cells, mitochondria and chloroplasts
80s found in eukaryotic cells
Describe the structure of a bacteria cell
Cell wall contains murein
capsule
cell-surface membrane
70s ribosomes
circular strand of DNA
plasmids
Does HIV have a murein or a cell wall
no
Why do scientists use very thin slices of alveolar tissue with the optical microscope
Alveolar tissue one cell think
Allow the light to shine through to see the individual cells
