Paper 1

movement, reprodution, sensitivity, growth, respiration, excretion, nutrients, homeostasis

a process that takes place in the mitochondria. Involves the breakdown of food in order to release energy which is stored in ATP.

the removal of waste products from metabolism

the regulation of internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes.

detail of the cell revealed by the electron microscope

each organelle has a specifc role within the cell; they work together for the cell's survival.

- plug it in
- clip down slide on stage
- turn on light source
- look through eyepiece lens
- choose objective lens
- adjust coarse focus until image is sharp and visible
- adjust fine focus
- observe specimen

coloured chemicals that bind to molecules in a specimen

- makes cells visible
- increases contrast as different components of cells take up different amounts of the stain
- details in cell can be seen e.g. organelles

- methylene blue
- iodine solutiuon
- acetic orcein

using more than one chemical stain as different stains bind to specific structures. Can be used to show contrast between organelles, tissues and microorganisms.

the number of times larger an image is compared with the actual size of the object.

the ability to distinguish between two separate points that are very close together. More resolution = more detail.

200nm

0.1nm

a printed scale in the eyepiece which is divided into 100 units. Its relative size changes depending on the objective lens being used. The units are EPUs (eye piece units)

consists of a microscope slide which has a fine and accurate scale engraved on it. It is 1mm long and divided into 100 units, meaning each small division is 10 micrometers.

- place stage micrometer on stage of microscope and focus on low power
- line scale on stage micrometer with scale of eyepiece graticule by rotating eye piece and moving slide
- count number of divisions on the eyepiece graticule that correspon to 1mm on tge stage micrometer
- calculate distance in micrometers of one division on eyepiece graticule.
- repeat process for medium power
- repeat process for high power, however the whole stage micrometer cannot be seen so find two points that align and count divisions.

scans a specimen, either on or below the surface

- specimens usually tagged with fluorescent dyes
- laser causes dye to give off fluorescent light
- light is focused though a pinhole
- scans specimens at different depths
- mulitple images can be combined by a computer to produce a 3D image.

- images are high resolution and high contrast
- 3D image

- observe fungal filaments within the cornea of a patient with fungal corneal infection
- used during endoscopy

0.004nm

- sample must be prepared carefully to withstand the vacuum inside the microscope
- air is pumped out the microscope and a beam of electrons is fired down through a series of electromagents lenses which focus the electrons onto a very fine spot
- the beam moves back and forth across the specimen (SEM) or through the specimen (TEM)
- electrons are detected and turned into a black and white image
- false colour may be added afterwards

scanning electron microscope

transmission electron microscope

can be whole, must be stuck down, dry and coated in gold

must be sectioned very thinly

3D

2D

to study the surfaces of objects

to study the structure of objects/organelles

x200,000 and 2nm resolution

x2,000,000 and 0.2nm resolution

400-700nm

low resolution compared to electron microscope

observing some living things e.g. single cell later

low resolution compared to electron microscope

highlights individual components of cells

resolution often not as high as TEM

cannot be used to look at living things

nucleoplasm contains chromatin, nuclear envelope, nuclear pores, nucleolus, outer membrane is continuous with endoplasmic reticulum

- contains DNA that codes for proteins
- during cell division chromatin condenses into chromosomes

- double membrane that encloses DNA and keeps it separate from reactions in the cytoplasm

- allow entry of molecules for DNA replication
- exit of mRNA for protein synthesis

- manufactures ribosomes

- allows easy transport of substances

cisternae, rough ER, smooth ER

allow transport within cell

synthesise and transport proteins

synthesise and transport lipids and steroids

2 subunits made of rRNA and protein

protein synthesis, binds to and moves along mRNA and translates it

cisternae, secretory vesicles

modifies proteins and packages them into vesicles or lysosomes

fuse with cell surface membrane to release hormones or enzymes from the cell

vesicles which contain hydrolytic enzymes

isolate potentially harmful enzymes from cell, break down material ingested by phagocytes, break down old organelles, break down cells when they die.

double membranes, inner membrane folded to form cristae, matrix contains small ribosomes, circular DNA, enzymes

isolates reactions in aerobic respiration (ATP production)

increases SA for enzymes to be attached

codes for proteins

for aerobic respiration

double membrane, thylakoids stacked into grana, stroma containing enzymes, starch grains, small ribosomes, DNA, lipid droplets

isolates photosynethis reactions

increases SA for chlorophyll molecules to be attached

contain enzymes for photosynthesis

for membranes

composed of 9 sets of 3 microtubules

form the spindle fibres during nuclear division to control the separation by chromatids and chromosomes

microtubules, microfilaments, intermediate filaments

support cell organelles position, enables movement of organelles e.g. vesicles and proteins, strengthens cell and maintains shape.

composed of 2 central microtubules surrounded by 9 pairs, many short like projections (cilia) and longer whip-like protection (flagellum in prokaryotes, undulipodium in eukaryotes).

sliding of microtubules brings about movement, using ATP, cilia in bronchi and trachea waft mucus towards throat, cilia in oviduct waft ovum towards uterus.

cell sap contained within tonoplast (vacuolar membrane)

maintains turgor for support, storage e.g. dissolved suagrs, mineral ions, enzymes etc.

made of cellulose secreted by cell, contain pores penetrated by plasmodesmata, middle lamella

support and protection, allows cell to become turgid and prevents it from osmotic bursting

links neighbouring cells

cements neighbouring cells together.

prokaryotes: only one membrane: cell surface
eukaryotes: many membrane bound organelles

prokaryotes: does not contain these
eukaryotes: mitochondria always present, chloroplasts present in some plant cells

prokaryotes: composed of peptidoglycan
eukaryotes: present in plant cells, composed of cellulose

prokaryotes: single circular strand of DNA
eukaryotes: linear DNA

prokaryotes: aerobic, takes place on mesosomes
eukaryotes: aerobic and anaerobic, takes place in mintochondria

H and O

C, H, O usually in the ratio Cx(H2O)x

C, H, O

C, H, O, N, S

C, H, O, N, P

long chain molecule made of linked repeating units called monomers

sugars (monosaccharides)

amino acids

bonds are made, water is removed

bonds are broken using water

atoms or molecules that have an uneven charge

positive ions due to loss of electrons

negative ions due to gain of electrons

inorganic ions dissolved in water

control osmosis, nerve impulses, muscle contraction