2.2 biological molecules Flashcards
How are two water molecules bonded?
hydrogen bond by condensation reaction
Is oxygen negative or positive
slightly negative
Is hydrogen negative or positive
slightly positive
What type of molecule is water
dipolar molecule
Key features of water
- solvent
- high specific heat capacity
- metabolic
- strong cohesion
- large latent heat of vaporisation
Solvent
- allows transport round the animal/plant = xylem or blood plasma
- used for respiration in organisms
High specific heat capacity
- lot of energy required to raise the temperature of cell
- means that temperature remains constant so enzymes do not denature
large latent heat of vaporisation
- takes lots of heat energy to evaporate water
- so organisms can cool down without loosing lots of water
Metabolite
- involved in photosynthesis, condensation, hydrolysis
- 90% plasma made of water
Strong cohesion
- water molecule ‘sticking’ together
- allows contious column of water up the xylem = easier to draw a column than individual molecules
- provides surface tension so allows small invertebrates to live on surface providing a habitat
10 inorganic ions
- calcium
- phosphate
- chloride
- hydrogencarbonate
- hydrogen
- hydroxide
- nitrate
- sodium
- potassium
- ammonium
What do calcium ions help to do
regulate transmission of impulses
regulate protein channels
formation of blood clots
What do phosphate ions help to do
component of the cell membrane
component of bone
component of ATP and nucleic acid
What do nitrate ions help to do
required for growth and repair
provide source of nitrogen for protein synthesis
What do hydroxide ions help to do
role in bonding between biological molecules
DNA base pairing
What do potassium ions help to do
nerve transmisson
reabsorption of water in the kidneys
open the stomata
What do sodium ions help to do
transport of glucose and amino acids across cell surface membrane
transmission of nerve impulses
What do ammoninum ions help to do
deamination of amino acids in the liver and kidneys
What do chloride ions help to do
maintaining pH balance during carbon dioxide transport
What do hydrogencarbonate ions help to do
carbon dioxide transport in blood
What do hydrogen ions help to do
hydrogen bonding
control of pH
transport of carbon dioxide
ATP formation
What type of molecule is starch
storage
What bond does amylose have
alpha 1-4 glycosidic bond
straight chain
What bond does amylopectin have
alpha 1-4 glycosidic bond = monomer
alpha 1-6 glycosidic bond = branches
Function of starch
easily hydrolised into soluable sugars
compact
insoluable so no osmotic effect
not involved in chemical reactions
What bond does glycogen have
alpha 1-4 glycosidic bond and alpha 1-6 glycosidic bond
Is glycogen a storage molecule in animals or plants
animals
Is starch a storage molecule in animals or plants
plants
What bond does cellulose have
beta 1-4 glycosidic bond
Structure of cellulose
alternate molecules inveretd by 180 degrees
What are the bonds between each beta glucose molecule
hydrogen bonds
Structure of triclyceride
glycerol head
3 fatty acid tails = hydrophobic
What bond do lipids form
ester bond by condensation reaction
What is a saturated lipid
single covalent bond
solid at room temperature
pack closely together
What is an unsaturated lipid
double bond
oil at room temperature
kink in chain so don’t pack closely together
What organelles are in an animal cell ?
- cytoplasm
- centriole
- cytoplasm
- mitochondria
- lysosome
- cilia
- nuclear envelope
- nucleus ( nucleolus )
- SER
- RER
- ribosome
- golgi apparatus
- cell surface membrane
- cytoskeleton
What organelles are in a plant cell?
- golgi apparatus
- chloroplast
- lysosome
- vacuole
- SER
- RER
- mitochondria
- nucleus (nucleolus)
- nuclear envelope
- cellulose cell wall
- cell surface membrane
- cytoskeleton
What structures are in a prokaryotic cell?
- flagellum
- circular DNA
- large genetic material
- cytoplasm
- ribosomes (70s)
- cell surface membrane
- plasma membrane
- capsule
- mesosome (aerobic respiration)
- pili
Describe a light microscope
uses light as a form of image
light passes through/reflects on the surface
living and non-living things
Describe a transmission electron microscope
uses electrons to form an image
electrons transmitted through to see internal structures
only dead or non-living
Describe a scanning electron microscope
uses electrons as a form of image ( can be 3D)
electrons are reflected
only dead or non-living
Laser scanning microscope
uses a laser beam to scan an objecct to create a 3D image of the reflected photons
Magnification/ resolution of light microscope
useful magnification x1500
max magnification x 2000
resolution 200 nm (0.2 um)
Magnification/ resolution of transmission electron microscope
magnification x 1,000,000
resolution 0.2 nm
Magnification/resolution of scanning electron microscope
magnification x 1,000,000
resolution 3-20 nm
Disadvantages of TEM’s
only used with thin specimens
cannot observe live specimens
don’t produce a colour image
Disadvantage of LSCM’s
can cause photodamage to the cells
slow process
Disadvantages of SEM’s
lower resolution of TEM’s
cannot observe live specimen
don’t produce a colour image
Definition of magnification
how many times bigger the image is than the real life object
Define resolution
ability to distinguish between objects that are close to each other
how clear the image is
Why is staining important
makes cells more visible
increase contrast
identify cell components
Production stages of making proteins
- nucleus stores DNA which is copied to make mRNA for the process of transcription
- this leaves through the nuclear envelope pore and attaches to the ribosome on the RER
- the ribosome reads the genetic code through translocation and synthesises a protein
- RER processes protein
- golgi body modifies the protein and creates a secretory vesicle
- protein fuses with cell surface membrane by exocytosis
Role of cytoskeleton
- provides mechanical strength
- intracellular movement (within the cell) aids cells with tracks to move along
- cellular movement via cilia or flagella
What is the cytoskeleton made up of
- microfilaments : movement of cells by moving against each other
- microtubules : organelles moved along the fibres using ATP
What is a prokaryotic cell wall made from ?
peptidoglycan
What is a eukaryotic cell wall made from?
cellulose / chitin / lignin
Method of reducing sugar test
- add benedicts reagant to a test tube sample
- heat in water bath above 75 degrees
- if a reducing sugar is present a brick red coloured preciptate will have formed
Method for non-reducing sugars (sucrose)
- add dilute hydrochloric acid to sample and heat in water bath until boil
- add sodium hydrogencarbonate to neutralise the solution
- use pH indicator paper to see if it has been neuatralised (will be green)
- add benedicts reagant and heat
- if brick red coloured preciptate is present then positive test
