2.1 cell structure Flashcards
name all the organelles you could find in an eukaryotic cell
nucleus, nucleolus, nuclear envelope, RER, SER, golgi apparatus, ribosomes, mitochondria, lysosomes, cellsurface/plamic membrane, centrioles, cell wall, chloroplats, permenant/non p vacuole, flagella, cilia
describe the organelles in the nucleus and all their functions
nucleus- contains cell activity by controlling the transcription of DNA which contains instructions to make proteins, contains organisms genome
nucleolus- makes ribosomes by making RNA
chromatin- consists of DNA and proteins
nuclear envelope- a double membrane which has nuclear pores to allow substance to move between the cell and nucleus
describe the function and structure of the RER
rough endoplasmic reticulum - folds processes proteins made by the ribosomes (adds a carbohydrate group), has ribosomes attached to it
describe the function and structure of the SER
smooth endoplasmic reticulum - synthesises and processes lipids, phospholipids and steroids, has no ribosomes attached
describe the function and structure of the golgi apparatus
processes and packages new proteins and lipids into vesicles, made of membrane bound flattened sacs
what is the function of ribosomes and whats the difference between free ribosomes?
site of protein synthesis
free - float free and are not attached to the RER
describe the role of mitochondria and their structure
site of aerobic respiration where ATP is produced
smooth outer membrane
folded inner membrane that form cristae
matrix which contains enzymes
what is the role of lysosomes
contains digestive enzymes (lysozyme)
describe the function and structure of centrioles
involved with the seperation of chromosomes during cell division
small hollow cylinders, made of microtubules (9 pairs) held by supporting proteins
describe the flagella’s structure, function and where it’s found
made of 9 pairs of microtubules with 2 in the middle, basal body
outside the cell on the cell surface membrane
movement/locomotion of the cell
describe the cilia’s structure, function and where its found
made of 9 microtubules with 2 in the middle, basal body
outside surface of cell surface membrane
moves substances along cell surface
how does the cilia and flagella move
motor proteins move across generating a force which makes it beat
describe the function of a cell wall and what its made from
provides rigid structure and has a defense mechanism to protect against pathogens and is fully permeable
cellulose
are vacuoles permanent or non permanent in plant cells
permanent vacuoles in plant cells
non permanent vacuoles in animal cells
describe the structure of the vacuole and what it contains and stores
membrane (tonoplast) lined sacs that contain cell sap
stores water
are vacuoles fully permeable
no, selectively permeable
what type of membrane does a chloroplast have
describe the internal features of a chloroplast
double membrane
internal membrane = thylakoid
grana = stacked up thylakoid
grana joined by lamallae
inside fluid = stoma
what is the role of chloroplasts and what else do they contain thats different to other organelles
site of photosynthesis
contain DNA and ribosomes
what is the cytoskeleton
an extensive network of protein fibres
what is the function of the cytoskelton
structural support and strengthening
intracellular movement/ transport organelles within a cell
cellular movement
name the three protein fibres in cytoskeleton
microfilaments
microtubules
intermediate filaments
desribe the structure of microfilaments
narrowest 7nm
made of many linked monomers of protein actin in a double helix structure
actin filaments assemble and dissassemble quickly allowing movement
describe the structure of microtubules
largest 25nm
made of tubulin proteins in a hollow tube like structure consiting of 2 subunits
grows and shrinks quickly due to addition and removal of tubulin proteins
describe the structure of intermediate filaments and their role
8-10nm
made of multiple strands of fibrous proteins wound together permanent, structural role by bearing tension and maintain the shape of the cell
describe the role the nucleus plays in creating proteins
contains DNA which codes for the production of proteins and contains the nucleolus which manufactures ribosomes
describe the stages of protein synthesis
1.DNA is copied into a molecule of mRNA via transcription
2.mRNA strand leaves the nucleus through a nuclear pore and attaches to a ribosome on the RER
3.ribosome ‘reads’ the genetic instructions on mRNA and uses this code to synthesise a protein via translation
4.protein then passes into the lumen (the inside space) of the rough endoplasmic reticulum to be folded and processed
5.proteins transported by vesicles from the RER to the golgi apparatus and fuses to release the protein
6.golgi modifies the protein
7.protein leaves the golgi by secretory vesicles by pinching it off and fuse with cell surface membrane and undergo exocytosis
what is a prokaryote
a single celled organism that does not contain membrane bound organelles
name the structures always present in a prokaryotic cell
cell wall, plasma membrane, cytoplasm, circular DNA/nucleoid, ribosomes
name the additional structures found in a prokaryotic cell
flagellum, capsule, plasmids, pilli, mesosome, infolding of plasma membrane
what is the function of a capsule
final outer layer helps to protect bacteria from drying out as made from slime and protects from attacks from immune systems
what are plasmids
small loops of DNA contains genes that can be passed between prokaryotes
what is the function of pilli
attachment to other cells/surfaces and involved in sexual reproduction
what are mesosome
the infolding of plasma membrane, helps the formation of cell walls and associated with DNA during cell division
what is the infolding of plasma membrane used for in prokaryotic cells
may form a photosynthetic membrane and carry out nitrogen fixation
compare the size of a eukaryotic to a prokaryotic cell and the size of their ribosomes
prokaryotic cells are smaller and have smaller ribosomes to (70s) eukaryotic (80s)
what do cell walls contain in eukaryotic cells(plant), fungi and prokaryotic cells
plant - cellulose
fungi - chitin
pro- peptidogylcan and murien
compare how DNA is in euakrytotic cells to prokaryotic
eukaryotic - linear, seperate strands of DNA in chromosomes , wrapped around protein histones
prokaryotic - circular strand of DNA, no histone, proteins fold and condense, small loops (plasmids)
describe the endosymbiont theory
mitochondria and chloroplasts (and other organelles) were formally prokaryotes
what evidence in cells supports the endosymbiont theory
mitochondria and chloroplasts contain their own DNA and ribosomes
what is the magnification equation
magnification = image size/ actual size
what is magnification
the number of times larger an image is compared to the object
what is resolution
the ability to see two points separately as two points
to see detail
name 4 types of microscopes
light/ optical
laser scanning confocal
transmission electron (TEM)
scanning electron (SEM)
name the advantages and disadvantages of a light microscope
portable, easy to use, can see living or dead specimen, cheap
specimen need to be thin/transparent, max mag. of x1500 and res. of 200nm
what is observed with a laser scanning conofocal microscope and how does it observe
whole living specimen and their structures at different depths
uses laser light to scan and produce a computer image
what is observed how is it observed with a TEM
a thin sample of a dead specimen
eectrons pass through specimen, denser parts they pass less easily providing contrast
name the advantages and disadvantages of electron microscopes (TEM and SEM)
much higher magnification/resolution, produces detailed images of structures, SEM produces a 3D image and detailed surface view
very expensive, need trained staff, have to have dead samples as placed in vacuum
what is the maximum magnification and resolution of light, laser scanning conofocal, TEM, SEM microscopes
light = x1500, 200nm
LSC= x
TEM= x500000, 0.02nm
SEM=x100000, 0.5nm-1nm
how do you prepare a specimen
staining - helps to see cell by increasing contrast of structures to identify certain parts of a cell eg. methylene blue = nucleic acid turns blue
sectioning - embed specimen in wax, then cut thin
what is a stage micrometer and how many divisions and what size are they
a scale thats fitted on a cover slip and its divisions are a known size (10nm and there are 1000 divisions)
what is an eyepiece graticule
a scale that is in the eyepiece lens (units are aribitary)
how do you calibrate an eyepiece graticule
align the e.g and s.m
count how many divisions of the e.g correspond to a set number of s.m ddivisions
calculate how big one e.g is
what image does a laser scanning confocal microscope show
2D or 3D
coloured or back and white
what image does a TEM show
2D
black and white
what image does a SEM show
3D
black and white
