3 - Biological molecules

Question 1

stuff about water due to it having a hydrogen bond

Answer 1

it’s polar, meaning it’s a good solvent
unusually high boiling point
it’s less dense as a solid as it forms a tetrahedral arrangement
it has cohesive and adhesive properties leading to capillary action
it’s a coolant
very cool transport medium

Question 2

speedrun carbs

Answer 2

carbs are sugars aka saccharides. monosaccharides is one unit. polysaccharides have many units of C6H12O6.

Question 3

glucose

Answer 3

there are two types:

alpha - the OH is under in C1
beta - the OH is on top in C1

Question 4

condensation reactions

Answer 4

when the OH on C1 and C4 react together to form a water and a polysaccharide, which also forms a 1,4 glycosidic bond

Question 5

starch

Answer 5

starch is made from two polysaccharides:
amylose - formed by two alpha glucose
amylopectin - also formed by two alpha glucose but the glycosidic bond is on carbon 1 and 6

Question 6

hydrolysis reactions

Answer 6

you need water to break a glycosidic bond - that’s what a hydrolysis reaction is: the opposite of a condensation reaction

Question 7

cellulose

Answer 7

two beta glucose molecules tbh

Question 8

triglycerides

Answer 8

one glycerol, three fatty acids that’s joined with an ester bond in a condensation reaction

you should know how it looks, if not i’m very disappointed in you and you should google it rn

Question 9

phospholipid

Answer 9

a phosphate and two fatty acids

phosphate head is hydrophilic
tails are hydrophobic

Question 10

structure of an amino acid

Answer 10

amine group
r- group
carboxyl group

google it fam

Question 11

protein structure

Answer 11

primary - flat 2d

secondary - formed with hydrogen bonds (alpha helix/ beta pleated sheet)

tertiary - 3d, they have:
hydrogen bonds
hydrophobic/philic interactions
ionic bonds
disulphide binds

Question 12

sugar phosphate backbone

Answer 12

phosphodiester bond on 5’ to phosphate to 3’ on a sugar where a base is connected on 1’

Question 13

pyrimidines

Answer 13

has one carbon ring - thymine and cytosine

Question 14

purines

Answer 14

had two carbon rings - adenine and guanine

Question 15

base pairs

Answer 15

adenine + thymine - AT
guanine + cytosine - GC

Question 16

how to make maltose, sucrose and lactose?

Answer 16

A glucose + A glucosse > Maltose
Fructose + glucose > sucrose (normal sugar) Galactose + glucose > lactose (milk sugar)

Question 17

Which 2 enzymes are involved in DNA replication?

Answer 17

DNA helicase

Catalyses the breaking of hydrogen bonds between base pairs and the untwisting of the DNA helix

DNA polymerase

Catalyses the formation of phosphodiester bonds between nucleotides in the new DNA strand

Question 18

Describe the process of semi conservative DNA replication.

Answer 18

1. DNA helicase catalyses the splitting of hydrogen bonds and unwinding of the double helix structure

2.The 2 separate polynucleotide chains have exposed bases

3.Free nucleotide pairs complementarily bond to form hydrogen bonds

4.DNA polymerase catalyses the condensation of the new nucleotides to form phosphodiester bonds

5. The new molecule twists to form a double helix

Question 19

What is a codon?

Answer 19

Base triplet, 3 bases which code for an amino acid

Question 20

What is a gene?

Answer 20

A section of DNA with a complete sequence of codons for an entire protein.

Question 21

What is degenerate code?

Answer 21

Amino acids can be coded for by more than one codon.

Question 22

Define transcription.

Answer 22

Conversion of genetic code to sequence of nucleotides in mRNA that leave the nucleus via nuclear pores

Question 23

Describe the process of DNA transcription.

Answer 23

1.DNA helicase catalyses the breaking of hydrogen bonds between the bases

2.Free RNA nucleotides base pair to the template/antisense strand

3.Phosphodiester bonds from - catalysed by RNA polymerase

4.Transcription stops at the end of the gene - completed strand is mRNA

5.mRNA detaches from antisense and leaves via nuclear pores to ribosome

Question 24

Describe the process of translation

Answer 24

1.mRNA binds to small subunit of ribosome

2.tRNA with a complementary anticodon binds to the start codon (AUG) in the large subunit - the amino acid is activated (using ATP)

3.Another tRNA enters the ribosome, and binds to the next mRNA codon

4.The two amino acids form peptide bonds and is catalysed by peptidyl transferase (part of rRNA)

5.The ribosome moves along the RNA, the first tRNA is released, the second tRNA becomes the first and another tRNA binds to the large subunit

Question 25

What happens after translation?

Answer 25

protiens get sent to the golgi appartus for futher modifications

Question 26

How do you carry out and interpret the Biuret test?

Answer 26

test for protiens

1.Add Biuret A (NaOH)

2.Add few drops of Biuret B (CuSO4 - copper II sulfate)

3.If proteins are present - BLUE TO PURPLE

Question 27

How do you carry out and interpret the emulsion test?

Answer 27

test for lipids

1.Add ethanol and mix to dissolve lipid

2.Add water and mix

3.If there are lipids present, a cloudy, white emulsion layer is on top

Question 28

How do you carry out and interpret the iodine test?

Answer 28

test for starch

1.Add potassium iodide (KI) and shake

2.If starch is present colour change from yellow/brown to blue/black

Question 29

How do you carry out and interpret the Benedict’s test?

Answer 29

test for reducing sugars
(for non-reducing just add HCl beforehand)

1.Add equal volume of Benedict’s Reagent (copper II sulfate)

2.Heat in water bath (100oC) for 3-5 minutes

3.If there are reducing sugars, Cu2+ reduced to red Cu+ ions

Colour change from blue > green > yellow > red

> > > > > increasing reducing sugar conc.