Cell structure

Question 1

What is magnification?

Answer 1

Magnification is how much bigger an image appears compared with the original object. Magnification produced by microscopes is LINEAR

Question 2

What is resolution?

Answer 2

Resolution is the ability of an optical instrument to see or produce an image that shows fine detail

Question 3

How do you calculate total magnification?

Answer 3

Total magnification = eye piece magnification x objective lens magnification

Question 4

How do you calculate image size? What is the equation triangle?

Answer 4

Image = Actual size x magnification
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Question 5

What is a optical microscopes resolution and magnification?

Answer 5

Optical microscopes = x1500 and resolution of 200nm (cant distinguish objects closer than this)

Question 6

What are the advantages and disadvantages of optical microscopes?

Answer 6

Optical microscopes advantages:
Cheap, easy to use, portable, can study whole live specimens
Disadvantages:
Low resolution and magnification

Question 7

What is the resolution of electron microscopes?

Answer 7

Electron microscopes have a wavelength of 0.004nm

Question 8

Discuss transmission electron microscopes

Answer 8

Transmission electron microscopes chemically fix their specimens (dehydrate and stain). Electrons [ass through the specimen. They have a magnification of 2-50 million times

Question 9

What image to transmission electron microscopes produce?

Answer 9

Transmission electron microscopes produce a 2D black and white image called an electron micrograph

Question 10

What type of image does a scanning electron microscope produce?

Answer 10

Scanning electron microscopes produce a black and white 3D image

Question 11

How do scanning ekecetron microscopes work?

Answer 11

Scanning electron microscopes use electrons that bounce off the specimen after it has been fixed and covered in a film of metal. This occurs in a vacuum.

Question 12

How do laser scnanning microsopes work and whatvare their advantages?

Answer 12

laser scanning microscopes (confocal) scan the objects point by point. The advantages are:
High resolution and contrast image, theyhave depth electivity and so can study whole live specimens

Question 13

How would you study a live specimen?

Answer 13

Studying a live specimen:

• School light microscope and adjust the iris diaphragm to reduce illumination of specimen.
• use light interference and a dark background to observe them

Question 14

How do you prepare a slide?

Answer 14

Preparing slides:

1. dehydrate
2. embed in wax
3. slice sections

Question 15

What are 5 stains and what do they show?

Answer 15

Stains:

• Methyline blue - general
• acetic orsein- DNA stained red
• Eosin- stains cytoplasm pink
• sudan red- stains lipids
• iodine- cell walls yellow and starch blue

Question 16

What is the scale used for microscopes?

Answer 16

The scale used is logarithmic meaning it goes up in steps where there is a 10 fold increase

Question 17

what organisms are eukaryotic?

Answer 17

Animal cells, plant cells, fungi cells and protoctista are all examples of eukaryotic cells

Question 18

What are some similarities between animals and plant cells?

Answer 18

Similarities between animal and plant:

Nucleus, nucleolus, ribosomes, mitochondria, endoplasmic reticulum Golgi, plasma membrane, vesicles

Question 19

Where are some differences between animal and plant cells?

Answer 19

Differences between animal and plant:

• Plants have vacuole
• plants have chloroplasts
• plants have amyloplasts containing starch
• plants have a cell wall

Question 20

What is the structures and functions of nucleus?

Answer 20

Nucleus:

• nuclear envelope with pores, chromatin, nucleolus
• stores genetic information, provides instructions for protein synthesis

Question 21

What is the definition of chromatin?

Answer 21

Chromatin- DNA packaged with histone proteins

Question 22

What is the structure and functions of Rough ER

Answer 22

Rough ER:

• Cisternae provide large surface area for ribosomes
• ribosomes for protein synthesis

Question 23

What is the structure and functions of smooth ER

Answer 23

Smooth ER:

• cisternae
• lipid metabolism, synthesis of cholesterol steroid hormones lipids and phospholipids and absorption and transport of lipids

Question 24

What is Golgi structure and function?

Answer 24

Golgi:

• Near vesicles , membrane bound flattened sacs
• protein modification (adding sugars or lipids), folding of proteins and packaging into vesicles for storage or movement

Question 25

What is mitochondria structure and functions?

Answer 25

Mitochondria: - Double membrane, cristae, matrix and 2-5 micrometres big - ATP production, self replicate - more abundant in active cells

Question 26

What are the features and function of lysosomes?

Answer 26

Lysosomes: - Contain hydrolytic enzymes, abundant in phagocytic cells - Compartmentalise enzymes from the rest if the cell to prevent damage, recycle - formed from the golgi

Question 27

What is the structure of chloroplasts?

Answer 27

Chloroplast structure: - stroma - grana made up of thylakoids - intergranal lamellae - double membrane - loops of DNA - starch grains

Question 28

What is the function of chloroplasts?

Answer 28

Chloroplasts are responsible for photosynthesis

Question 29

What is the structure and function of vacuoles?

Answer 29

Vacuoles: - membrane called a tonoplast, contains fluid - maintain turgidity and therefore support plant structure

Question 30

What si the structure and function of cilia and undolipodia?

Answer 30

Cilia and Undolipodia: - contain microtubules and formed from the centrioles - Move mucus, receptors and movement of sperm

Question 31

Structure and function of ribosomes

Answer 31

Ribosomes - made of rRNA in the nucleolus - free floating ribosomes synthesise proteins used in the cell - ribosomes bound to RER synthesise proteins exported out of the cell

Question 32

Structure and function of centrioles

Answer 32

centrioles: - 2 bundles of microtubules arranged at 90 degrees, made of tubulin and the subunits are arranged to form a hollow cylinder - form the mitotic spindle and cilia and undulipodia

Question 33

Structure and function of cell wall

Answer 33

Cell wall: - Bundles of cellulose in plants - chitin in fungi - prevents cell from bursting, gives strength and support and is permeable

Question 34

Structure of the cytoskeleton

Answer 34

Cytoskeleton structure: it is a network of protein structures within the cytoplasm -microtubules made of tubulin (transport, mitotic spindle, cilia and undulipodia) -microfilaments made of actin (support and strength) -intermediate filaments made of proteins (anchor the nucleus and aid in cell to cell communication)

Question 35

What are the steps for making and secreting a protein?

Answer 35

Making and secreting a protein: 1. gene is transcribed into mRNA which passes out of nuclear envelope via pores to ribosomes 2. mRNA translated into a protein and the protein gets assembled 3. the molecules of protein pass to cisternae of RER and vesicles then pinch off 4. vesivles move alone microtubules by motor proteins to Golgi 5. proteins modified at Golgi from cis--- trans end and vesicles pinch off and move to plasma membrane 6. vesicles fuse and protein is released out of the cell by exocytosis

Question 36

What are similarities of prokaryotic and eukaryotic cells?

Answer 36

Similarities between prok and euk: - plasma membrane - cytoplasm - ribosomes - DNA and RNA

Question 37

What are differences between prokaryotic and eukaryotic cells?

Answer 37

Differences between prok and euk: - Euk ribosomes are 80S-----prok are 70 S - Prok have cell wall of peptidoglycan/miurein - prok are smaller - euk have well developed cytoskeleton + centrioles and prok have no centrioles - prok have no membrane bound organelles - euk have nucleus with DNA and prok have naked loop of DNA - prok divide by binaery fission---- euk divide by mitosis

Question 38

What are some features of prokaryotic cells that are absent in eukaryotic cells?

Answer 38

Prokaryotic cells features: - protective waxy capsule - plasmids - pili (act as passage for plasmid dna to move from plasmid to plasmid) - flagella

Question 39

Why could prokaryotic cells and mitochondria be looked at similarly?

Answer 39

Mitochondria are thought to be derived from prokaryotic cells as they share similar features. e.g. loops of DNA. (chloroplasts also share these)

Question 40

What is the theory of how eukaryotic cells arose from prokaryotic cells called?

Answer 40

The theory of how eukaryotic cells arose from prokaryotic cells is called the endosymbiont theory.

Question 41

Describe viruses

Answer 41

Viruses are acellular non living particles. - 20-300 nm big - contain nucleic acids - have a capsid (protein coat)