Assorted Flashcards
What is the formula for glucose?
c6h12o6
What is maltose made up of?
Glucose + glucose
What are the structural differences between glucose and ribose? (2)
- glucose is c6h12o6, ribose is c5h10o5
- ribose is pentose sugar, glucose is hexose sugar
How do the properties of water lead to surface tension? (3)
- water molecules are polar
- therefore form hydrogen bonds
- therefore are cohesive
What are the least dense cell components?
glucose, enzymes, ATP, amino acids, proteins
If you separate out ER through centrifugation then how can you next separate SER and RER? (2)
Use smaller intervals of density,
RER is more dense
Explain why cells carry out mitosis (2)
Growth/repair,
because this needs genetically identical cells
Explain what happens to the DNA content and number of chromosomes by the end of interphase? (4)
- DNA replication
- therefore DNA content doubles
- new chromatids are formed
- but number of chromosomes stays the same
Why are two results seen in plants for anaphase in root tip not identical? (3)
- student may have picked different part of root tip
- it is difficult to identify stage of mitosis
- different plants have different rates of growth
Explain how pollen tubes could still grow in the presence of an inhibitor (2)
Because some mRNA could still be made, so some protein synthesis can take place.
Describe process of translation (5)
- mRNA is attached to ribosome
- tRNA is attached to a specific amino acid
- tRNA anticodon binds with mRNA codon
- peptide bonds form between amino acids
- process involves stop/start codons
In which stage does independent assortment take place?
metaphase I
In which stage does crossing over take place?
prophase I
Describe process of crossing over (4)
- Homologous chromosomes line up
- chromatids overlap
- break in DNA occurs
- genetic information exchanged between chromatids
What are chiasmata?
overlaps in chromatids
How can you use antibiotics to identify whether a bacterium is gram positive or negative? explain (3)
If antibiotics worked then gram positive because gram positive have a cell wall with more peptidoglycan, therefore is a target site for antibiotic.
How are proteins made in cells? (5)
- DNA unzips because hydrogen bonds are broken
- mRNA made by complementary base pairing
- mRNA leaves nucleus and attaches to ribosomes
- tRNA anticodon attaches to mRNA codon
- amino acids form peptide bonds in translation
Why might a point mutation mean an enzyme can’t work anymore? (3)
Mutation would affect active site,
change in sequence of amino acids,
glucose would not bind so no enzyme substrate complex.
Describe how a quaternary structure is formed after protein synthesis? (2)
Polypeptides fold up into a helix or beta pleated sheet arrangement,
two or more polypeptides join together by H bonds/disulphide bridges.
How would a DNA molecule with 4 nucleotides be arranged?
Two in a line, two upside down antiparallel
Why do some bases not code for amino acids? (2)
Some are start/stop codons, some are introns (non-protein coding)
How do you work out activation energy?
Max potential energy - initial potential energy
Why is reaction rate faster for amylopectin than amylose when both put in with amylase? (2)
- active site is more complementary to amylopectin
- amylopectin has more terminal glycosidic bonds/more side branches
What are liposomes?
Spherical sac surrounded by phospholipid molecules, containing medicine or treatment.
Some drugs prevent proper formation of spindle fibres. How can this help treat cancer? (3)
- fibres can’t contract
- contraction of fibres needed to cause chromatids to separate
- so chromatids cannot be pulled to opposite poles so new cells can’t be made
How does the nitrogen experiment support DNA replication theory? (4)
DNA is replicated semi-conservatively
- heavy DNA disappears after first cycle
- after one replication DNA is intermediate as one strand comes from original DNA and one from a newly constructed strand
- as you get more DNA being formed, the increase is all
due to newly formed strands, which are all light DNA
How could you use a time vs mean absorbance of colorimeter to find initial RoR?
Draw a tangent to the curve of the graph.
Tangent drawn following only the first few seconds of the curve.
Read off single values for absorbance and time.
Calculate gradient of the line to find the rate.
Why do fruits only go brown after being cut?
Substrate and enzyme contained within cells so cannot mix, and don’t have oxygen supply
so when they get cut they can mix and get oxygen.
Why does lemon juice prevent browning? (1)
change in pH!!!!
