Topic 1: Cell Biology

example of eukaryotic cells

animal and plant cells

example of prokaryotic cells

bacterial cells

organelle definition

structures in cell that have different functions

list all subcellular structures in animals and what they do

1. nucleus- contains genetic material that controls activeties of cell

2. cytoplasm- where chemical reactions happen, contains enzymes, gel-like

3. cell membrane- controls what goes in and out of cell

4. mitchondria - aerobic respiration

5. ribosomes- protein synthesis

list all subcellular structures in plants and what they do

1. rigid cell wall- made of cellulose, supports and strengthens cell

2. permanent vacuole- contains cell sap

3. chloroplasts- photosyntehsis and contains cloprophyll which makes the plant green

list all subcellular structures in bacterial cells and what they do

1. cell wall

2. cell membrane

3. cytoplasm

   • dont have true nucleus, have one single circular strand of DNA

   • contain plasmids

   • no membrane bound organelles

explain light microscopes

1. use light to form image

2. let us see individual cells and large subcellular structures

explain electron microscope

1. better magnification

2. better resolution

formula for magnification

magnification = image size/real size

method to prepare a slide

1. add a drop of water to the middle of a clean slide

2. cut up an onion and seperate it into layers

3. use tweezers to peel off epidermal tissue from layer

4. add a drop of iodine solution

5. place coverslip on top

method of using light microscopes

1. clip slide onto stage

2. select lowest powered objective lens

3. use coarse adjustment knob to move stage up below objective lens

4. look down eyepiece and adjust until image is roughly in focus

5. adjust focus with fine adjustment knob until you get a clear image

what is differentiation

process by which a cell changes to become specialised for its job

how are sperm cells specialised

1. for reproduction

   • flagella + streamlined head: swimming to egg

   • mitochondria: energy for movement

   • acrosome with enzymes: break down layers of the egg

how are nerve cells specialised

1. carry electrical signals

   • axon is covered with a fatty sheath, which speeds up nerve impulses

   • branched connections: connect to other nerve cells to form a network

how are muscles specialised

1. for contraction

   • long: space for contraction

   • mitochondria: energy for contraction

how are root hair cells specialised

1. for absorbing water and minerals

   • large SA: more water can move up

   • mitochondria: energy for respiration

how are xylem tubes specialised

1. for transporting water + minerals up plant

   • made of dead cells

   • strengthened with lignin

   • movement of water: transporation

how are phloem tubes specialised

1. for transporting food and dissolved sugars

   • elongated living cells with small pores: allows cell sap to flow

   • transport in both directions via translocation

what do chromosomes contain

genetic information: 23 pairs

descibe the cell cycle

1. cell grows and chromosomes replicate

2. chromosomes are pulled to each end of the cell

3. cytoplasm and cell membrane divide to form two new cells

describe binary fission

1. DNA and plasmid replicates

2. DNA moves to poles

3. The membrane pinches in

4. The cytoplasm divides

what does a culture medium contain

carbs, minerals, proteins, vitamins

how are microorganims grown in an agar plate

1. hot agar jelly poured into petri dishes which is left to cool and set

2. inoculating loop used to transfer microorganisms to culture medium

3. lid is taped on and incubated so microorganims can grow

list the two ways to grow microorganisms in a lab

1. agar jelly

2. nutrient broth solution

why do petri dishes and culture media need to be sterilised before use

to kill any bacteria

why do petri dishes need to be stored upside down and sealed with tape

1. prevent condensation from lid disrupting growth

2. stop microorganisms from air getting in

how are inoculating loops sterilised

by passing through a flame

why in school laboratories, do cultures need to be incubated at 25°C.

harmful pathogens are more likely to grow

what is a stem cell and list examples

1. undifferntiated cells

   • embryonic stem cells

   • meristem

   • adult stem cells

explain embryonic stem cells

• found in early human embryos

• differentiate into any cell and be cloned

• replace faulty cells: make insulin producing cells (diabetes) and nerve cells (paralysis)

• painless technique

explain adult stem cells

• found in bone marrow

• replace faulty blood cells

• patient can give consent

what is therapeutic cloning

embryo is produced with the same genes as the patient

• stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment

for and against - stem cell research

against:

1. portential human life

2. banned in some countries

3. embryos cant consent

for:

1. unwanted embryos from fertility clinic which would usually be destroyed

2. curing exsiting suffering patients is more important than the rights of embryos

explain meristem cells

• can differentiate into any type of plant cells

• can be used to produce clones

definiton of diffusion

spreading out of particles from an area of high concentration to an area of low concentration

list factors that affect rate of diffusion

1. difference in conc

2. temperature

3. SA of the membrane

definition of osmosis

movement of water particles from a high concentration to a lower concentration through a partially permeable membrane

definition of active transport

movement of particles against a conc gradient using energy from respiration

describe active transport in root hair cells

1. take in water and minerals from soil

2. require energy from respiration

describe active transport in the gut

1. occurs when there is a lower conc of nutrients in the gut but high conc of nutrients in blood

how are exchange surfaces specialised for exchanging materials

1. thin membrane: short diffusion distance

2. large SA: lots of substances can diffuse at once

• in animals: lots of blood vessels - get stuff in and out of blood quickly

explain role of aveoli in gas exchange

aveoli: maximise diffuse of O2 and CO2

• large SA:Vol

• moist lining for dissolving gases

• thin walls

• good blood supply

explain role of villi in gas exchange

villi: increase SA so food is absorbed more quickly into blood

• single layer of surface cells

• good blood supply to assist quick absorption

where does gas exchange happen

in the lungs: transfer O2 to the blood and remove waste CO2

how are the gills adapted for gas exchange

1. gill filaments: big SA to exchange gases

2. lamellae: large SA, have thin surface layer to minimise distance gases have to diffuse

3. lamellae: blood cappilaries to speed up diffusion

4. blood flows through lamellae in one direction and water flows in opposite: maintains large conc gradient between water and blood

how are leaves adapted for gas exchange

1. stomata underneath leaf: allows CO2 to diffuse through

2. flattened shape: increases area of exchange surface = more effective

3. air spaces inside leaf: increase area of surface - more CO2 to get into cells

describe the food test praticals

glucose - benedicts + heat - brick red - blue
protein - biuret - lilac - blue
starch - iodine - orange/brown - blue/black
fats - ethanol + water + shake - cloudiness - colourless

method for osmosis

1. peel potato and use a cork borer to create 3 identical cylinders

2. measure length using ruler and mass using balance

3. place cylinders into test tubes; add 10cm³ of 0.5 molar sugar solution to first test tube, 10cm³ of 0.25 molar sugar solution to second, add 10cm³ of distilled water to third

4. leave cylinders overnight

5. remove cylinders and dry them with paper towel to remove excess water

6. measure length and mass again

7. calculate % change between length and mass

variables for osmosis

1. CV: vol of solution, temp, time, sugar needed

2. IV: conc of sugar solution

3. DV: mass of potato cylinders

method for culturing microorganisms

1. sterilse petri dishes, nutrient broth solution and agar: prevents contamination

2. sterile inoculating loop by passing it through bunsen burner

pros and cons of adult stem cells

pros:

• procedure is safe

• patients recover quickly

• reliable technique

cons:

• risk of infection from procedure

• can only treat a few diseases

• procedure can be painful

risks of using stemcells to treat illness

• can become infected with viruses

• using infected stem cells to treat patient risks transferring viral infection to patient