2A-cell division and structure Flashcards
cell surface membrane function
1-regulates movement of substances into and out of the cell
2-receptor molecules respond to chemicals hormones
Nucleus
structure=1-nuclear envelope contains many pores
2-chromosomes made from protein bound DNA
3-chromatin
4-Nucleolus
Function=1-controls transcription of DNA + instructions to make proteins
2-pores allow RNA/substances to move between nucleus and cytoplasm
3-Nucleolus makes ribosomes
Mitochondria
structure=1-double membrane with inner folded christae
2-matrix contains emzymes for respiration
Function=1-site of aerobic respiration to produce ATP
2-Abundance in very active cells
Chloroplasts
Structure=1-surrounded by double membrane
2-thylakoid membranes stacked to form grana
3-Grana linked by lamellae
Golgi apparatus
1-processes and packages new lipids and proteins
2-makes lysosomes
3-makes golgi vesicle
Golgi vesicle
1-stores and proteins made by golgi apparatus
2-transports them out of the cell via cell-surface membrane
Lysosomes
1-contains lysoszymes that digest invading cells+breaking down worn out cell components
2-cell membrane keeps lysozymes separate from cytoplasm
Ribosome
Structure= floats free in cytoplasm or attached to RER
-made of RNA and proteins + surrounded by cell membrane
Function= Protein synthesis occurs
RER
folds and processes proteins made at ribosomes
SER
synthesises and processes new lipids
cell wall
supports cells and prevents it changing shape
Plant cells
1-cellulose cell wall with plasmodesmata-channels for exchanging substances between cells
2-vacuole
3-chloroplasts
Plant cells
1-cellulose cell wall with plasmodesmata-channels for exchanging substances between cells
2-vacuole
3-chloroplasts
4-starch cells
fungal cells
1- chitin cell wall
2-unicellular
3-NO chloroplasts
Epithelial cells structure and function
1-Lots of microvilli,increase surface area for absorption
2-lots of mitochondria to produce ATP and provide energy for active transport of molecules
3-
Red blood cells
1-No nucleus so more room for Hb
2- capillary shaped easily move through blood
3- strong structural proteins as free floating
sperm cells
1- streamlined easily move
2-lots of mitochondria to produce ATP and release energy for movement
3-Enzymes in head to digest though the egg.
tissue
group of similar cells that work together to carry out a particular function
Organ
group of different tissues that work together to perform a particular function
organ system
group of organs that work together for a particular function
Prokaryotic cell structure
1-Flagellum- rotates to make cell move
2-free floating smaller ribosomes- protein synthesis
3-cell-surface membrane-made of lipids and proteins
4-murein glycoprotein cell wall
5-capsule of secreted slime- protect from immune response
6-plasmids- small loops of DNA that contain genes for antibiotic resistance + passed between prokaryotes
7-free floating circular super-coiled DNA with no associated proteins
8-smaller than eukaryotes
9-no membrane bound organelles
10-smaller ribososmes
How are prokaryotic cells different
1-cytoplasm has no membrane bound organelles 2-smaller ribosomes 3-circular supercoilled DNA lies free in cytoplasm with no associated proteins 4-Murein cell wall 5-capsule of secreted slime 6-plasmids 7-flagellum 8- Smaller than eukaryotic cells
Prokaryotic cell replication binary fission
1-circular DNA replicates once and plasmids replicate variable number of times
2-cell gets bigger and DNA and plasmids move to opposite ends of the pole
3-cytoplasm divides
4-2 daughter cells produced with 1 circular DNA and a variable number of plasmids
Viruses structure
1-acellular-nucleic acid surrounded by proteins
2-attachment proteins
3-capsid coat
4-core of circular supercoilled DNA or RNA that isn’t associated with proteins
Viral replication
1-virus attaches to Host cell receptor protein due to complementry specific tertiary structure
2-genetic material released into the cell
3-genetic material and proteins replicated by hijacking host cell machinery
4-viral components assemble
5-released from host cell causing cell death
Magnification
how much bigger and image is compared to specimen
Magnification calculation
size of image/ size of real object
resolution
how well a microscope can distinguish between 2 points that are close together
if microscope lens can’t distinguish between 2 points
-increasing magnification has no effect
optical microscope
-use light to from an image
optical microscope
-use glass to focus light to from an image
optical microscope disadvantages
1- lower magnifications than EMs
2-Lower resolution than EMs
3-can’t observe specimens smaller than light wavelength
4-preparation may distort specimen
TEMs
- focus beam of elections onto specimen using electromagnets
- denser parts of specimen absorb more electrons so appear darker
TEMs
- focus beam of elections onto specimen using electromagnets
- denser parts of specimen absorb more electrons so appear darker
- in a vacuum
SEMs
- scan a beam of electrons across specimen
- knocks electrons of specimen which gather at cathode ray tube and produce image
- in a vacuum
TEMs advantages
1-give high resolution images- show small
2- higher magnification than optical
TEMs disadvantages
1-Vacuum so non living specimens 2-only used on thin specimens 3-expensive to buy 4-requires training 5-NO colour
SEMs advantages
1-used on thick specimens
2-3D specimens and images
3- higher magnification than optical
SEMs disadvantages
1-vacuum non-living specimens
2-give lower resolution than TEMs
3-expensive to buy
4-requires training
Temporary mount
-specimen suspended in drop of liquid
Preparing specimen with microscope slides
1-pipette small drop of water to slide
2-place thin section of specimen on slide
3-add drop of stain
4-add cover slip preventing bubbles appearing
Microscope artefacts
objects that aren’t part of the specimen and appear due to incorrect preparation
How to distinguish artefacts
-repeat different methods of preparing a specimen and comparing differences
why are artefacts prevalent in EMs
-requires lots of preparation
cell fractionation steps
1-homogenisation-breaking up cells
2-filtration-
3-Ultracentrifugation
Homogenisation
1-vibrate cells or grinding cells in blender
2-releases organelles into solution
3-Ice cold solution-reduce enzyme activity that break down/hydrolyse organelles
4-isotonic- doesn’t affect WP so osmosis doesn’t damage cells
5-pH buffer-optimum temp for enzymes and proteins to prevent denature
Filtration
1-filtered through gauze to separate large tissue debris from organelles which are smaller and pass through
Ultracentrfugation
1-pour in test tube and spin at low speed, heavier organelles gather as pellet and lighter remain in supernatant
2-supernatant drained and spun at higher speed
3-repeated at higher speeds, as lighter organelles gather as pellet
ultracentrifugation of organelles heaviest to lightest
Naughty-Nucleus Clever-chloroplasts Monkey's-mitochondria Like-lysosomes Eating Red- Endoplasmic reticulum Raspberries-ribosomes
Interphase stages of cell cycle
Gap Phase 1
synthesis
gap phase 2
Gap phase 1
1-cell grows
2-new organelles made
3-new proteins made
synthesis
1-cell replicates DNA via transcription and translation for mitosis
Gap phase 2
1-cell keeps growing
2-proteins needed for cell division made
Interphase
1-cell carries out normal functions
2-Gap phase 1-cell grows, new proteins and organelles made
3-synthesis of DNA-DNA unravelled and replicated doubling genetic content
4-Gap phase 2-proteins for cell division made
5-ATP content increases providing energy for cell division
Prophase
1-chromosomes condense getting shorter and fatter
2-centrioles move to opposite ends of the pole leaving network of spindle fibres
3-nuclear envelope degraded releasing chromosomes in the cytoplasm
Metaphase
1-chromosomes line up along the equator
2-centromere of chromosomes attaches to spindle fibre
Anaphase
1-centromeres divide separating each pair of sister chromatids
2-spindle fibres contract pulling each sister chromatids to opposite ends of the pole centromere first
Teleophase
1-Chromosomes uncoil and become long and thin chromosomes
2-Nuclear envelope forms around chromosomes
3-cytokineses occurs as cytoplasm splits
4-2 genetically identical daughter cell produced
5-daughter cells enter interphase
Rate of mitosis determined by
1-cell type
2-environmental conditions
cancer
uncontrolled cell division by mitosis caused by mutations in genes forming a tumour that invades surrounding tissue
chemotherapy
1-prevent synthesis of enzymes need for DNA replication
2-not produced IN gap phase 1 cant enter interphase 3-cell kills itself
Radiation
1-damage DNA
2-disrupts synthesis of DNA replication
3-cell kills itself
mitotic index
number of cells with visible chromosomes / total number of cells observed
Do viruses have a cytoplasm
No bacteria do
viruses don’t
