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What happens at primary level?
- Peptide bonds are formed.
- sequence of amino acids are formed.
What is at the secondary structure?
- Hydrogen bonds formed
- Initial folding of polypeptide chain.
What is In the tertiary structure?
- Overall 3D shape.
- Ioinic bonds are formed.
Formation of hydrogen bonds between two molecules of water?
- Between O and H at adjacent molecules.
- Between electropositive and electronegative.
- Water molecule is polar.
Why is waters ability to act as a solvent important?
- Supports metabolic reactions.
- Allows ions to separate.
- Allows organism to absorb minerals.
Structure of amino acids molecule,
- Look in revision guide and practice
Structure of collagen
- Peptide bonds between amino acids.
- Every 3rd Amino Acid is glycine.
- Three polypeptide chains.
- Hydrogen bonds between polypeptide chains.
Structure of Haemoglobin
- Hb is globular.
- Hydrophobic group on inside and hydrophilic on outside.
- 4 polypeptide chains, 2 beta and 2 alpha.
Which bases bind to which bases?
- A-T
- C-G
What are the two factors which can causes variation?
- Genetic.
- Environment
What are the use of remaining combinations?
- Some are used as stop codons.
- Several triplets code for one amino acid
Describe the process of translation
- mRNA moves to ribosomes.
- tRNA molecule binds to mRNA.
- Anticodons bind to codons.
- Specific amino acids bind to codons.
- Peptide bonds between Amino Acids are formed.
Structural Differences between RNA and DNA
- Uracil instead of thymine.
- RNA only had one strand, DNA had 2.
- RNA is shorter
Why is complementary base pairing important?
- DNA can be replicated without error.
- Allows hydrogen bonds to form.
Why is the glucose molecule suited to its function?
- Insoluble, can be transported easily.
- Easily broken down, to produced ATP.
Structural similarities between deoxyribose and other components of DNA molecule.
- Part of the nucleotide.
- Attached to phosphate.
Name the bond formed between two amino acids as how is it formed?
- Peptdie bond.
- Condensation reaction between carboxyl group and amine group.
Where are hydrogen bonds found in biological molecules
- In protein secondary structure.
- Between polypeptide chains in tertiary structure.
- Between chains of cellulose.
- Between strand of DNA.
Roles of cholesterol in living organism
- Regulates fluidity In phospholipids bilayer.
- Makes the skin waterproof.
How is the molecular structure of cholesterol similar to carbohydrate?
- Both contains C,H and O.
Why is glycogen a good storage molecule?
- It is compact.
- Lots of branches for enzymes to attach to.
- Can be broken down easily.
Similarities between DNA and RNA
- Both have a sugar-phosphate backbone.
- Both have four different nitrogenous bases.
- Both contain a pentose sugar.
Differences between DNA and RNA
- DNA contains thymine and RNA uracil.
- DNA has double stranded, RNA is single stranded.
- DNA only found in nucleus. RNA found in Nucleus and cytoplasm
Why is mRNA molecule shorter than a DNA molecule?
- mRNA only copies one section of DNA.
- DNA compromises many genes.
How does high temperature disrupt a tertiary structure protein?
- High kinetic energy.
- Protein molecule vibrates.
- Ionic bonds break.
- Change in 3D shale.
How to test for lipids
- Ethanol and water.
- Present=white emulsion.
How to test for reducing sugar
- Benedicts solution.
- Present=Brick-red precipitate.
How to test for protein
- Biuret I and II
- present=Lilac colour.
Water molecule structure
- Hydrogens are delta positive.
- Oxygens are delta Negative.
- Hydrogen bonds between water molecules.
How does a Amino Acid bond on?
- Peptide bonds forms.
- Between Amine group and Carboxyl group.
- Condensation reaction.
How to R groups interact to determine the tertiary structure?
- Some E groups attract/repel.
- Disulfide bonds between cysteine atoms.
- Ionic bonds between oppositely charged R groups.
Structural differences between glycogen and collagen.
- Glycogen= Branched. Collagen=Linear.
- Glycogen=Non helical. Collagen=Helical.
- Glycogen= Glycosidic bonds. Collagen=Peptide bonds.
Which sugar is the final products of the digestion process?
- Beta glucose.
Why are different enzymes involved in each stage of the digestion process?
- Enzymes are specific.
- Substrates are different shapes.
- Active site and substrates need to be complementary.
Explain the term biological catalyst
Speeds up metabolic reactions
What is the colour of iodine solution in the presence of starch?
- Black
How are hydrogen bonds formed?
- Between oxygen and hydrogen atoms.
- Between electronegative and electropositive molecules.
Effect of high temperature on the structure of the membrane
- Phospholipids have more KE.
- Larger gaps between phospholipids occur.
- Causes phospholipids to melt.
- Proteins denature.
Functions of membrane within cells.
- Form vesicles.
- Provides surface area for attachment of enzymes/ribosomes.
- Seperates contents of Organelle and cytoplasm.
How does the plasma membrane contribute to cell signalling?
- Release of molecule by exocytosis.
- Glycoproteins acts as receptor.
- Receptors are specific.
- Shape of receptor and signal are complementary.
- Attachment of signal molecule causes change.
How are vesicles move between organelles.
- Cytoskeleton.
- Move along Microtubules.
- Uses ATP
Examples of active transport
- Ions into root hair cells.
- hydrogen ions out of companion cells.
Outline the process of budding in yeast
- Nucleus divides.
- Organelles move into bulge.
- bulge pinches off.
Functions of glycoproteins in the cell surface membrane
- Act as antigens.
- Act as cell receptors.
- Cell recognition.
- Cell adhesion.
- Allows communication across membrane.
Types of cells in the phloem tissue
- Companion cell.
- Sieve tube element.
Independent Assortment of homologous chromosomes.
- Occurs in metaphase 1 and 2.
- So homologous pairs have different alleles.
Crossing over
- Occurs in prophase 1.
- Chromatids will have new combinations of alleles p.
- Produces large number of allele combinations.
Why are new branches seen growing from a position just under the bark of the cut surface?
- This is where cambium is found.
- Mitosis occurs in cambium.
- New cell specialised.
Locations where growth occurs in plants.
- Cambium.
- Meristem.
Why does meiosis need to have twice as many stages as mitosis?
- To halve the number of chromosomes.
- To separate homologous pairs.
What feature of DNA is changed as a result of mutation?
- Sequence of nucleotides.
Effects mutation can have on the structure and function of proteins
- Different primary Structure.
- Can be shorter due to deletion or stop codon.
- Can be longer due to insertion.
- Could be unchanged due to silent mutation.
- Function could be worse.
Why must genetic material replicate before mitosis?
- So cells are genetically identical.
- So both cells receive a full copy of DNA
What is a homologous pair of chromosomes?
- A pair of chromosomes which have the same genes.
- They are the same length.
- One maternal and one paternal.
- Attach to each other during meiosis
Where can meristematic tissue found?
- Apex of root.
- Apex of shoot.
How are products of meiosis different to the products of mitosis?
- Cells produced aren’t genetically identical in meiosis.
How is cell division in plants different to cell division in animals?
- Cell wall forms between new cells in plants.
- Only occurs in meristem for plants.
- No centriole in plants
Where in plants does cell division occur?
- Meristem
Why are lungs considered to be an organ?
- They are a group of tissues that work together.
- To carry out gas exchange.
Adaptations of a guard cell
- A vacuole, To take up water.
- Mitochondria, to generate ATP.
How o alveoli create a surface for efficient gas exchange?
- Wall is once cell thick, provide short diffusion pathway.
- Squamous cells provide a short diffusion pathway.
- Elastic fibres recoil, maintains conc. gradient.
- Large number of alveoli provided large SA.
- High SA:V ratio.
Why do large multicellular organisms needs a transport system?
- Low SA:V ratio.
- High metabolic rate.
- Diffusion distance is too great.
- To prevent build up of CO2.
ECG full name
- Electrocardiagram.
Why is there a delay between the excitation of the atria and ventricles?
- Allow time for atria to contract properly.
- Allow time for ventricles to fill.
- So ventricles do not contract too early.
Why is the excitation wave carried to the apex?
- So contraction starts at the bottom.
- To push blood upwards.
- Complete emptying of ventricles.
What is tidal volume?
- The volume of air taken in.
- During a normal breath.