2A. Cell structure and devision

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what is the cell surface membrane?
Found on surface of cells, made of lipids and proteins. Regulates movement of substances in & out of cell. Has receptor molecules
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What is the nucleus?
surrounded by nuclear envelope. contains chromosomes and a nucleous. controls cells activities. DNA makes proteins. Nucleolus makes ribosomes
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What is mitochondria?
double membrane, inside folded called cristae, inside that is the matrix which has enzymes for respiration. its the site for aerobic respiration > ATP
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what is chloroplast?
double membrane, thylakoid membranes, stacked to form grana, grana link by lamellae. This is where photosynthesis happens, in grana or storm
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What is golgi apparatus?
fluid filled membrane bound sacs, vesicles on edges. processes and packages new lipids and proteins. makes lysosomes
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what is golgi vesicle?
fluid filled sac inn cytoplasm, membrane, produced by golgi app. Stores lipids & proteins transports the outta cell
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what are lysosomes?
round surrounded by membrane. has digestive enzymes called lysozomes kept separate from cytoplasm. digest invading cells
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What are ribosomes?
small & floats free in cytoplasm or attached to RER. made of proteins and RNA. no membrane. site where proteins are made
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what is the RER?
system of membranes enclosing a fluid filled space. covered with ribosomes. folds and processes proteins
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what is the SER?
same but no ribosomes. synthesises and processes lipids
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what is the cell wall?
surrounds cells, made of carbs cellulose. chitin in fungi. supports cells and prevents them changing shape
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WHAT IS THE CELL VACUOLE?
membrane bound (tonoplast) found in cytoplasm. has cell sap. maintains pressure in cell and keeps it rigid. stops wilting. isolates unwanted chemicals
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Name a specialised cell
epithelial cells adapted to absorb food quick - villi & folds called microvilli increase S.A, lots of mitochondria. Red blood cells - no nucleus to carry more haemoglobin & oxygen Sperm - lots of mitochondria for energy
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What is the organisation of cells?
Cells are grouped together to form tissues, which form organs, which form organ systems.
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how are prokaryotic cells different than eukaryotic?
prokaryotic are smaller and less complex
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How is the structure of prokaryotic different?
no membrane bound organelles in cytoplasm, no nucleus, circular DNA, murrain cell wall
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what mayhems prokaryotic cells also have?
one or more plasmids, capsule surrounding cell and flagella
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how does a prokaryotic cell replicate?
BINARY FISSION - circular DNA and plasmids are replicated and cell divides procuring two daughter cells, each has singles copy of DNA and many of plasmids
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do viruses under go cell division?
No they are non living and acellular. instead they invade host cells & use their machinery to replicate themselves
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what is the structure of a typical virus?
no cell surface membrane, ribosomes, cytoplasm. have a capsid with attachment proteins which cling to host cell
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what is the formula to find magnification?
mag = size of image % real life size
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What is the definition of magnification?
how much bigger the image is than the sample
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What is the definition of resolution?
how detailed the image is, based on the microscopes ability to distinguish between two points that are close together
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Pros and cons of optical microscopes
max resolution 0.2 micrometers, max mag x 1500. can't see small organelles, can see nucleus
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Pros and cons electron microscopes
max Resolution 0.0002 micro, max mag 1 500 000. can see more organelles, black and white images
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what are TEMS?
use electromagnets to focus a beam of electrons, transmitted through specimen. denser look darker. high resoltution so can see internal structures of organelles ie chloroplast,. need a vacuum slo has to be dead
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what are SEMS?
scan a beam of electrons through specimen. knocks of electrons which are gathered in a cathode ray tube to form image. can be 3D image, good for thick specimens but low resolution
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what are artefacts?
like dust or air bubbles, not part of specimen. first scientists had to repeatedly prepare specimens i different ways to identify them
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How does cell fractionation work?
1. Homogenisation - can break up cells by vibrating them or grinding in a blender, releasing organelles. must be ice cold and isotonic.2. Filtration - get rid of big bits, filter. 3. Ultracentrifugation - spun to get heaviest mass repeated faster
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what cells can't keep dividing?
multicellular organism cells
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what is interphase and mitosis?
interphase is a period of growth and DNA replication, mitosis is cell division
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what happens in PROPHASE?
chromsomes get shorter & fatter, centrioles (proteins) move to opposite poles, form fibres called spindle. nuclear envoplepe breaks down
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what happens in METAPHASE?
chromosomes line up along middle and attach to spindle to centromere
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what happens in ANAPHASE?
centromeres divide separating chromatids, spindles contract and pull chromatids to poles making v shape
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what happens in TELOPHASE?
chromatids at poles uncoil becoming long and thin. nuclear envelope forms round each group of chromosomes so now two nuclei. cytoplasm divides (cytokinesis) > 2 genetically identical daughter cells
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what can uncontrolled growth or mitosis cause?
cancer, tumours that invade surrounding tissue, when there's a mutation in a gene that controls cell division
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what do cancer treatments aim to do?
aimed at controlling the rate of cell division, can kill normal cells whoopsie
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how do you prepare stained squashes of root tips?
cut 1cm from tip as growth occurs here so mitosis, put in boiling tube with 1m hydrochloric acid in bath of 60 degree for 5 mins.
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how would you use an optical microscope to observe the stages of mitosis in the root tip?
cut 2mm form tip, break tip and spread evenly, add drops of stain. use lowest objective lens giving low mag, use coarse knob to bring stage up & down, adjust focus
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how do you calculate mitotic index?
this is the proportion of cells in a sample undergoing mitosis. Number of cells with visible chromosomes % total number if cells observed
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Other cards in this set

Card 2

Front

What is the nucleus?

Back

surrounded by nuclear envelope. contains chromosomes and a nucleous. controls cells activities. DNA makes proteins. Nucleolus makes ribosomes

Card 3

Front

What is mitochondria?

Back

Preview of the front of card 3

Card 4

Front

what is chloroplast?

Back

Preview of the front of card 4

Card 5

Front

What is golgi apparatus?

Back

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