2.1- Cell Structure Flashcards
1
Q
Magnification
A
- Describes how much bigger an image is comapred to original.
- produce linear magnification
2
Q
Resolution
A
- clarity of an image
3
Q
Optical Microscopes
A
- used in schools and hospitals
- cheap, easy to use, portable, study whole living specimens
- magnification up to x1500
- resolution up to 0.2ym
- use light in wavelength 400-700nm
4
Q
Calculate Magnification
A
total magnification= power of objective lens x power of eyepiece lens
5
Q
Photomicrograph
A
photograph of image seen using an optical microscope
6
Q
Laser Scanning Microscope
A
- also called confocal microscopes
- use a laser to scan and assemble pixels into an image
- high resolution and depth selectivity
- used in medical profession
7
Q
Electron Microscopes
A
- use electrons with wavelength of 0.004nm
- better resolution as electrons wavelength is x125000 smaller than light
8
Q
‘Transmission electron microscope
A
- electrons pass through
- has to be dehydrated and stained with metal salts
- form a 2d black and white image called an electromicrograph
- mag= x2,000,000
9
Q
‘Scanning electron microscope
A
- electrons bounce off
- 3D image
- mag= x200,000
- black and white
- vacuum and coated in metal
10
Q
Staining Specimens
A
- Methlyene blue= all purpose stain
- Acetic Orcein= stains chromosomes red
- Eosin= stains cytoplasm
- Sudan Red= stains lipids
- Iodine= stains cellulose yellow and starch blue
11
Q
Preparing Specimens
A
- Fixing= Chemicals like formaldehyde are used to preserve specimens
- Sectioning= dehydrated with alcohols then embedded in a mould with wax. then sliced thinly
- Staining= Treated with multiple stains
- Mount= Secure to slide and coverslip
12
Q
Calculations with Magnification
A
- I= A/M
- ym= micrometre
- m-mm-ym-nm
13
Q
Using graticules
A
- scale is arbitrary
- stage graticule can calibrate an eyepiece graticule= 1mm long in 100 divisions of 0.01mm
- use x4 first and bring sg into focus and align it together, work out how much 1 epu is by sg/number of divisions on eg and do for all mags
14
Q
Eukaryotic Cells
A
- nucleus in nuclear envelope containing DNA
- nucleolus with RNA, making ribosomes and chromosomes unwind
- cytoplasm
- cytoskeleton- protein filaments(actin or microtubules) that move organelles, cells or contraction of muscle cells
- plasma membrane
- vesicles
- ribosomes
15
Q
Nucleus
A
- surrounded by double membrane
- stores genome and control centre
16
Q
Nuclear envelope
A
- Contains pores
- seperates nucleus from cell
- some substances dissolve through fused areas of double layer like ribosomes
- some go through pores in it like mRNA
17
Q
Nucleolus
A
- Contains RNA and chromatin (genetic material)
- where ribosomes are made
- chromatin is DNA wrap around histone proteins, when cells divides it condenses into chromosomes
18
Q
Rough Endoplasmic Reticulum
A
- membranes containing cavities (cisternae) and coated in ribosomes
- cisternae transports substances
- proteins assemble on these ribosomes, pass through cisternae then to golgi
19
Q
Smooth Endoplasmic Reticulum
A
- membranes with cisternae
- has enzymes that catalyse reactions like synthesis of cholesterol, lipids, phospholipids, hormones
- involved with absorption, synthesis and transport of lipids
20
Q
Golgi Apparatus
A
- stack of mb flattened sacs
- vesicles bring materials to and from
- proteins are modified by adding sugar or lipids, being folded then packaged into vesicles and are pinched off to cell or plasma membrane
21
Q
Mitochondria
A
- rod shaped and 2-5ym long
- double membrane with fluid-filled matrix of cristae
- site of ATP production during aerobic respiration
- self replicating
22
Q
Chloroplasts
A
- large= 4-10ym long with double membrane
- has stacks (granum) of sacs called thylakoids containing chlorophyll
- contain DNA and site of photosynthesis( light is trapped by chlorophyll and used to make ATP, then H2 reduces CO2 using ATP to make carbs occurs in stroma)
23
Q
Vacuole
A
- surrounded by membrane called tonoplast
- filled with water, solutes
- makes cell stable
24
Q
Lysosomes
A
- small bags formed from golgi
- contain hydrolytic (digestive) enzymes and keep them separate
- abundant in most cells that digest pathogens
- bin for cells organelles
25
Q
Cilia and Undulipodia
A
- protrusions from cell and both contain microtubules
- formed from centrioles
- cilia beat away mucus
- cilia has receptors and allows cell to detect signals about environment
- only cell to have undulipodia (longer cilia) is a spermatozoon
26
Q
Ribosomes
A
- small, spherical, 20nm
- made of ribosomal RNA
- made in nucleolus as 2 separate subunits that combine in cytoplasm
- some attach to RER for synthesising proteins
- free ribosomes are site of assembly for proteins
27
Q
Centrioles
A
- have 2 bundles of microtubules made of tubulin protein subunits in a (9x3)+2 cylinder at right angles
- before a cell divides the spindle forms from centrioles and chromosomes attach to it and motor proteins pull chromosomes to opposite ends
- centrioles multiply and line up beneath plasma membrane then microtubules sprout from each centriole forming a cilia/undulipodium
28
Q
Cytoskeleton
A
- microfilaments= made of actin, 7nm diameter, give cell support
- intermediate filaments= 10nm, anchor nucleus and cell-cell signalling
- microtubules= made of tubulin, 18-30nm diameter, support and form tracks and spindle and cilia
- motor proteins= myosins, kinesins and dyenins, walk organelles along track through cell and are enzymes and have a site that binds to and allows hydrolysis of ATP.
29
Q
Cellulose cell wall
A
- outside plasma membrane and made of cellulose fibres
- provides strength, support, shape and are permeable
30
Q
Making and Secreting a protein
A
- mRNA copy of the instructions (gene) for insulin is made in the nucleus then leaves through pore
- mRNA attaches to ribosome on RER and it reads instructions to assemble protein
- insulin molecules are pinched off in vesicles and go to golgi where they fuse there
- golgi processes and packages insulin molecules that are then pinched off in vesicles and move towards plasma membrane
- they fuse with plasma membrane and it opens to release insulin outside
31
Q
Prokaryotic cell
A
- similar= plasma membrane, cytoplasm, ribosomes, DNA, RNA
- different= smaller, less cytoskeleton, no centrioles, nucleus, mb organelles, peptidoglycan wall instead, smaller ribosomes, naked DNA, plasmids, flagella, pilli, divide by binary fission
