C6 Cells Flashcards
nucleus
- animals, plants
- control centre of the cell
- regulates all cell activity
- stores all genetic information
nucleolus
- animals, plants
- produces + assembles ribosomes, vital for protein synthesis
membrane
- animals, plants, bacteria
- thin protective layer forming the outside of a cell/cell organelle
- semipermeable
- provides protection
- keeps organelles enclosed
- regulates entry/exit of materials
wall
- plants, some bacteria
- separates interior/exterior of cell
- provides shape, support, rigour, protection
- 1st line of defence against pathogens/disease
cytoplasm
- animals, plants, bacteria
- everything INSIDE the cell membrane
- site of important chemical reactions
- helps move substances around the cell
cytosol
- animals, plants, bacteria
- the fluid/jelly-like part of the cytoplasm
- serves as a medium for the majority of a cell’s chemical reactions/processes
- structural support for cell
ribosome
- animals, plants, bacteria
- site of protein synthesis: reads mRNA strand
- vital for formation of proteins
mitochondria
- animals
- ‘powerhouse’ of the cell
- site of cellular respiration: produces ATP
- provides energy for all cell processes and organism function
rough endoplasmic reticulum
- animals, plants
- the part of the ER WITH ribosomes on its surface (which synthesis proteins + transport them to areas of cell
smooth endoplasmic reticulum
- animals, plants
- the part of the ER WITHOUT ribosomes on its surface
- synthesises + concentrates substances in cells (e.g. lipids, plasma, steroids etc)
vacuole
- animals, plants, bacteria
- processes, stores + disposes of waste products
- in plants: also helps maintain water balance, takes up majority of cell space
lysosome
- animals
- contains digestive enzymes that break down damaged/worn out cell parts
- destroy invading bacteria/viruses
chloroplasts
- plants
- contain chlorophyll, the main photosynthetic pigment
- convert light energy to sugars through photosynthesis
- vital for growth of plant, and for providing plant food for heterotrophs
golgi apparatus
- animals, plants
- packages + processes proteins, then exports them from the cell
- proteins are folded into a useable shape, and sometimes combined with other molecules (e.g. carbs/lipids)
vesicle
- animals, plants, bacteria
- small sac formed by a membrane and filled with liquid
- moves substances in/out of cell
- vital for transport of materials and disposal of waste products
flagella
- some plants, bacteria
- hairlike structure at the back of the cell, allows movement
cilia
- animals, plants, bacteria
- small, hairlike filaments on the cell body
- move in rhythmic, wave motions
- helps keep internal passageways free of debris/mucus
State the 3 principles of cell theory.
- all living things are made up of cell/s
- cells are the smallest unit of life
- new cells are produced through division of exisiting cells
Describe the overall function of cells.
- site of all biochemical reactions
- contain all the info needed for an organism to function (growth, repair, behaviour)
Describe the 2 types of non-cells. Why are they not cells?
VIRUSES
- genetic info incased in a protein coat (capsid)
- very small
- not cells: non-living, cannot reproduce without a host cell
PRIONS
- dysfunctional proteins
- rare, cause death to organism
- non-living
- both not cells as they are non-living.
TYPES OF CELL (2)
Describe the differences between the two types:
- definition
- DNA
- organelles
- size
- provide e.g. of types of organisms
Eukaryotes vs Prokaryotes
DEFINITION
- P: cells that don’t have membrane-bound nucleus or organelles
- E: cells that do have membrane-bound nucleus
and organelles
DNA
- P: not contained in a nucleus
- E: contained in a nucleus
MEMBRANE-BOUND ORGANELLES
- P: no
- E: yes, internal compartmentalisation
- both have ribosomes
SIZE
- P: very small (<10 micro m)
- E: larger depending on organism (animal 10-50 micro m, plant 50-150)
TYPES OF ORGANISM
- P: eubacteria (common bacteria), archaebacteria (extremophiles), cyanobacteria (perform Phs)
- E: protists (single celled), fungi, plants, animals
Describe why cells are so small providing 2 reasons.
- what will cause a cell to die or divide?
RATE OF METABOLISM
- the E demand of a cell is determined by its mass/volume
- small is efficient as less E is required
RATE OF MATERIAL EXCHANGE
- how quickly cells can exchange materials is determined by its SA:V
- smaller cells: larger SA and shorter transport differences have more efficient exchange
If the rate of material exchange cannot keep up with the rate of metabolism, the cell will die.
Describe the 3 types of microscope.
- lvls of mag/res
- what is visible
Describe electron microscopes (what, pros, cons).
LIGHT
- low mag + res
- coloured images (can’t use this as proof in exam Q)
- Visible: nucleus, chloroplasts, plant cell wall, cell membrane, vacuole
SEM (scanning)
- high mag + res
- b/w images
- display depth, 3D surface of an organism
TEM (transmission)
- very high mag + res
- b/w images
- display cross sections, ultrastructure of cells
ELECTRON MICROSCOPES (sem/tem)
- shoots electron beams through object
- Pros: higher res/mag - clearer image that can detect smaller structures
- Cons: cannot display colours
State the formulas used to find values from a microscope image (3), and how you would use them.
- what do you need to remember when counting/measuring cells?
I
A M triangle
- not in info book
- actual size of object = image size/magnification
1cm bar scale = actual cell size/diameter of drawing
- not in info book
- measure diameter of image with ruler
Actual size = FOV/no. cells across
- in info book
WHEN COUNTING/MEASURING CELLS, BE CAREFUL WHETHER IT IS WIDTH OR LENGTH.
CELL MEMBRANE STRUCTURE
- fluid mosaic model (how? functions?)
Components:
- phospholipids (structure, arrangement, properties)
- cholesterol (properties)
- proteins (2 types, functions)
FLUID MOSAIC
- fluid: phosphates are able to move freely
- mosaic: membrane is embedded with proteins and other elements
PHOSPHOLIPIDS
- hydrophilic head, hydrophobic tail
- arrange into a bilayer: tails align face inwards, heads align face into cell and out of cell
- restricts passage of many substances
- flexible: allows breaking/reforming of membrane for substance entry/exit
CHOLESTROL
- in animal cells
- moderates membrane properties
- immobilises membrane surface, reducing fluidity
- prevents crystallisation
- prevents small H2O molecules from permeating membrane
PROTEINS
- 2 Types: Integral (permanent, transmembrane (through)), peripheral (temporary, on surface)
- Functions: JETRAT
Junctions (connect cells)
Enzymes (provide AS for substrates)
Transport (of substances in/out of cell)
Recognition (between other cells)
Anchorage (for other substances)
Transduction (reception for hormones)
Describe how cell membranes are semi-permeable and what factors it is affected by.
- Semi-permeable: allow some substances in but not others
- Affected by: temp + pH (cause denaturing), ethanol
passive vs active transport
PASSIVE
- no ATP used, just KE
- high to low conc (‘with the flow’)
- with the conc gradient
ACTIVE
- ATP used
- low to high conc (‘against the flow’)
- against the conc gradient
Describe the types of passive transport (3).
- what is transported
- what they move through
- why does osmosis occur
Passive: Molecules move from a high to low conc.
SIMPLE DIFFUSION
- small, non-polar molecules
- the higher the conc gradient, the faster the rate of diffusion
- occurs across semi-permeable membrane
FACILITATED DIFFUSION
- larger, polar molecules
- the higher the conc gradient, the faster the rate of diffusion
- occurs through channel (integral) proteins
OSMOSIS
- net movement of free water molecules
- from a region of low conc of solute to high conc of solute
- occurs across semi-permeable membrane
Why?
- water is a universal solvent, and will bond with the solutes
- this means that in a solution with a high conc of solutes, there will be less free water molecules
- the free water molecules will move to equalise the solutions
- results in equal number of free water molecules either side, but more volume on the side with a higher solute conc
concentration gradient
the difference in concentrations between two areas (e.g. inside a cell and out)
solute
polar/charged molecules that are dissolved in water
What is osmolarity? Describe the 3 different types of solution that can occur, and where the free water molecules move.
Osmolarity is the measure of a solute conc in a solution that a cell is in.
HYPOTONIC
- low solute conc outside of cell, high conc inside
- free H2O moves into cell
- solution loses H2O
HYPERTONIC
- low solute conc inside of cell, high conc outside
- free H2O moves into solution
- cell loses H2O
ISOTONIC
- conc of solute is balanced both inside cell and in the solution
- no net H2O flow
Describe the effects of uncontrolled (hyper/hypo) osmosis on:
- animal cells
- plant cells
ANIMAL
- Hyper (solution has high conc): water leaves cell cytoplasm shrinks, cell shrivels
- Hypo (solution has low conc): water enters cell, cytoplasm expands, cell swells (possibly lysis occurs = burst)
PLANT
- effects of uncontrolled osmosis are the same as animal cells, except cells are not as affected as much
- cell wall keeps shape, prevents lysis or complete shrivelling
Describe the types of active transport (2).
MEMBRANE PUMPS
- pumps are carrier proteins that facilitate active transport
- move mols from low to high conc
- e.g. sodium potassium pump
BULK TRANSPORT
- large materials move in/out of cell enclosed in vesicles
- vesicles fuse with the cell membrane to allow entry/exit of the materials
- cell size is maintained via endocytosis (removes phos lipids) and exocytosis (adds phos lipids back)
Endocytosis
- substances move into cell
- cell membrane folds around substance, creating a vesicle that moves into the cell
- e.g. proteins, carbs
- liquids enclosed: pinocytosis (drinking)
- materials enclosed: phagocytosis (eating)
Exocytosis
- substances move out of cell
- vesicle joins with membrane, substances pushed out other side
- e.g. waste, proteins
vesicle
a ‘bubble’ of fluid and important materials, enclosed by a membrane
- used in active
chromosome
- what?
- how many in humans
- represented by?
- DNA molecules
- 23 pairs in humans (X shape)
- 46 single (half an X)
- represented by n (2n = diploid, n = haploid)
What should be considered when asked about DNA replication questions regarding no. of chromosomes?
- do not assume that n = 23, 2n = 46
- this is only in humans
- use n/2n unless specified otherwise
karyotype
- a visual representation of an entire organism’s chromosomes
- in humans there should be 22 pair of somatic chromosomes, 1 pair of sex chromosomes
- may indicate genetic disorders/mutations (e.g. extra chromosomes)
PMAT
- what
- very briefly state the purpose of each PMAT stage
- cytokinesis
- interphase
- the stages of cell division, a cycle
Prophase: chromosomes condense to form X shape
Metaphase: they line up in middle of cell
Anaphase: sister chromatids are pulled apart to either end of cell
Telophase: two nuclei form
Cytokinesis: cell splits, two new cells are formed
Interphase: normal cell state
MITOSIS
- functions (3)
- genetic material is…
- describe process (PMAT, ploidy, daughter cells)
FUNCTIONS
- make new somatic cells
- used for growth, repair, replace old cells
- for asexual reproduction in some organisms
- genetic material is conserved
PROCESS
- 1x PMAT
- 2n-(dna rep)-4n-2n (2x daughter cells)
- daughter cells are genetically identical to parent cells: have same set of DNA, any variation is due to random mutation
MEIOSIS
- functions (2)
- genetic material is…
- describe process (ploidy, PMAT daughter cells)
FUNCTIONS
- to make genetically unique gametes
- required for sexual reproduction
Genetic material is reduced
- gametes are haploid (n)
- undergo DNA rep
- parent cell divides 2x to produce 4 daughter cells, each haploid (n)
- during the process, genetic variation occurs
PROCESS
- 2x PMAT: Meiosis I (genetic variation occurs), Meiosis II (normal PMAT)
- 2n-(dna rep)-4n-(meiosis I)-2n-(meiosis II)-n (4x daughter cells)
- daughter cells are genetically unique to parent cells: due to genetic variation in Meiosis I
Describe the two types of genetic variation that occur during meiosis:
- when do they occur
- what do they cause
- what happens
- both occur during Meiosis I (1st PMAT)
- both cause genetic recombination (diversity between daughter cells)
CROSSING OVER
- occurs in Prophase I
- ‘segments’ of chromosomes (individual genes) swap between other chromosomes
INDEPENDENT ASSORTMENT
- occurs in Metaphase I
- chromosomes are separated at random to either side of the cell before division
sodium potassium pump
- what type of transport
- why is it needed
- describe process
- active transport, against conc gradient (high to low conc)
WHY
- in animal cells, K is needed in the cell, Na is needed out of cell
- however there is a higher conc of K inside cell, higher conc of Na out of cell
- active transport must be used to force transport against the conc gradient
PROCESS
- inside cell, Na binds to pump
- phosphate from ATP binds to pump, forces pump to open to outside of cell
- Na is released, K enters
- phosphate is released, pump opens back to inside
- K released, cycle continues
Describe how the structure of a sperm cell relates to its function (4).
FUNCTION
- produced by males to fertilise an ovum
- contain 1/2 genetic material required to form embryo
STRUCTURE
- streamlined shape: allows easy entry into ovum
- acrosomes: located on head, contain enzymes that identify the ovum, and break down ovum membrane
- flagella: allows movement
- midpiece: contains many mitochondria that allow the cell to move
Describe how the structure of an ovum relates to its function (3).
FUNCTION
- produced by females and released from ovaries
- contains 1/2 genetic material required to form embryo
STRUCTURE
- outer layer: follicle cells provide padding and protection, prevents multiple sperm from entering
- 2nd outer layer: sperm recognise it and bind to fertilise
- cell plasma/yolk: provides nutrition to developing egg
Describe how the structure of a oligodendrocyte relates to its function (1).
FUNCTION
- produce myelin, an insulating sheath on nerve fibres
STRUCTURE
- spokes provide myelin: can have up to 50 protruding from main cell body, providing myelin to up to 50 nerve fibres at once
Describe how the structure of a skeletal muscle cell relates to its function (4).
FUNCTION
- are the muscle cells in the tissue that is connected to the skeleton
- vital for body movement
STRUCTURE
- long cells: control movement of long bones
- myofilaments: create muscle contractions through sliding action
- many mitochondria: allow lots of ATP for movement
- multiple nuclei: enhance O2 uptake and tissue repair
Describe how the structure of a osteoblast relates to its function (2).
FUNCTION
- vital for bone synthesis + mineralisation
- synthesises molecules
STRUCTURE
- create a matrix: forms new layers of bone
- limited organelles: make cells robust and strong
Describe how the structure of a stem cell relates to its function (2).
FUNCTION
- able to transform into many specialised cells via dividing
- some stem cells are able to transform into many different types, some only limited types
STRUCTURE
- standard animal cell before it divides
- division: can divide asymmetrically (to produce a different cell) or symmetrically (to produce stem cells)
Describe how the structure of a photoreceptor cell relates to its function (2).
FUNCTION
- located in eye’s retina
- converts light to signals that the brain reads to produce an image
STRUCTURE
- two specialised types: cones (colour) and rods (b/w)
- photopigment: contains large amounts at a high density, allowing the majority of light photons to be absorbed
Describe how the structure of a root hair cell relates to its function (2).
FUNCTION
- located on the outside layer of root
- extract water and nutrients from the soil
STRUCTURE
- large SA:V ratio: long, skinny, tubular and horizontal shape allows efficient absorption
- thin cell walls: allow efficient transport into cell
Describe how the structure of a palisade mesophyll cell relates to its function (3).
FUNCTION
- main photosynthetic cell
STRUCTURE
- rectangular shape: cells fit together to maximise the number of cells in the leaf
- found in upper side of leaf: allow max light energy to penetrate the cell
- many chloroplasts: allow for a high Phs rate
- rigid: strong cell walls + inflexible for plant strength
Describe how the structure of a cardiac muscle cell relates to its function (2).
FUNCTION
- make up cardiac muscle in the heart
- responsible for contracting/relaxing to keep blood pumping
STRUCTURE
- elongated cells: interconnected through disks, branched for faster contraction
- striated: alternating filaments pull towards each other to perform contractions
- many mitochondria: cells perform efficient aerobic resp, are resistant to fatigue, allowing continuous contractions
Describe how the structure of a motor neuron cell relates to its function (2).
FUNCTION
- located in the nervous system
- responsible for allowing an organism to move by sending signals from the brain to the muscles
STRUCTURE
- dendrites: extend away from the cell to receive messages, increasing SA
- myelin sheath: fatty material over axons form a sheath, providing insulation, speeding up transmission of electrical impulses
