Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SNAB Biology Edexcel > Topic 2 > Flashcards

Topic 2 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

in genetic screening, why do carriers sometimes show a false positive

A

the recessive allele may be detected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what does implantation diagnosis consist of

A

embryos are created through IVF are tested to see if they carry faulty allele. Only the healthy embryos will be implanted
however the process is expensive and unreliable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

define allele

A

a version of a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

define a recessive allele

A

an allee which isn’t expressed when a dominant allele is present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

define dominant allele

A

an allele is always expressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

define incomplete dominance

A

neither allele is dominant over the other and the resultant phenotype is a mix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what symptoms can cystic fibrosis present in gas exchange

A

mucus can block bronchioles which leads to less O2 to the alveoli so smaller concentration gradients
thin layer of mucus can make it difficult for O2 and CO2 to diffuse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what symptoms can cystic fibrosis present in reproduction

A

in men - sperm duct blocked with mucus so sperm can’t leave the testes
in women - mucus blocks the cervix so sperm cannot reach the egg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what symptoms can CF present in digestion

A

blocks the pancreatic duct so digestive enzymes cannot reach the digestive system so food isn’t properly digestive and nutrients aren’t absorbed so there is difficulty gaining weight
enzymes trapped in the pancreas cause fibrosed cysts and damage insulin producing cells which can also lead to diabetes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does amniocentesis consist of

A

a syringe with a needle is inserted into the amniotic sac and fluid is extracted and foetal cells are then separated. This is cultured for 2-3 weeks
DNA is karyotyped, biochemical tests are also carried out on both the fluid and cells
this is when the foetus is 14-16 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what does chorionic villus sampling consist of

A

a syringe is inserted in the vagina to take a sample of embryonic tissue from the placenta (the chorionic villus).
DNA is karyotyped when the fetus is 8-10 weeks old

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why do people with CF have sticky mucus

A

the CFTR channel protein is non-functional therefore the Na+ channel (ENac) is always open so Na+ ions move into the cell and to the tissue fluid on the basal membrane
this causes the Cl- to move down the concentration gradient, water goes out from the mucus and into the cell and tissue fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are the factors that one must consider in relation to prenatal screening

A

risk of miscarriage, potential abortion, religious beliefs of right to life, cost of healthcare, risks/consequences of false positives/negatives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is meant by monohybrid inheritance

A

inheritance of 1 characteristic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

when can mutations occur

A

DNA replication, transcription and translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how do bodies decrease the viscosity of mucus on the apical membrane

A

Cl- is pumped into the cell across basal membrane
Cl- diffuses through open CFTR channels to outside apical membrane
Na+ diffuses down electrical gradient in mucus
Elevated salt concentration in the mucus draws water out of the cell and into the mucus via osmosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what did Meselon and Stahl’s experiment consist of

A
  1. E coli bacteria cultured in 15-N containing medium
  2. transferred into a 14-N containing medium
  3. DNA extracted after each generation and centrifuged into BaCl solution
    the heavier the DNA was, the deeper it sank in the test tube
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how did Meselon and Stahl’s experiment disproved the other theories

A
  1. In a conservative model, super heavy DNA would be expected with a newly lighter DNA as generations passed - 1 of each
  2. In dispersive, only 1 layer of equally dense DNA would be seen getting lighter and lighter - a mix of heavy and light
  3. Results showed intermediate strands of 1/2 heavy and 1/2 light after 1 generation which disproved conservative
    After 2 generations, 2 layers were shown, 1 intermediate and 1 light which disproved fragmentary
    semi conservative was 1 strand of intermediate and 1 strand of light in a double helix
17
Q

why isn’t heat used to accelerate reactions in organisms rather than enzymes

A

heat would damage cell tissues

18
Q

how do enzyme concentration affect the reaction rates

A

as the enzyme concentration increases, the rate increases as there is a higher chance of successful collisions therefore more enzyme-substrate complexes formed per unit of time so more products are released

19
Q

in experiments how could
temperature be controlled
pH be controlled

A

using a water bath with the temperature as close to optimum as possible
using a buffer solution as close to optimum

20
Q

what happens during semi-conservative replication of DNA

A
  1. DNA helicase breaks the hydrogen bonds between bases to unzip DNA
  2. DNA nucleotides align with their complementary bases and DNA polymerase creates phosphodiester bonds that join nucleotides together
  3. DNA ligase joins the partly formed strands together
  4. 2 identical daughter strands are created - 1 old and 1 new
21
Q

what did the conservative DNA replication model mean

A

1 whole completely new double helix is synthesised

22
Q

what did the dispersive/fragmentary DNA replication model mean

A

the new DNA molecule was created as a mix of old and new parts

23
Q

what does the induced fit hypothesis state

A

enzyme changes shape to fit substrate when substrate is near while lock and key model theorizes that the enzyme and substrate are always complementary in shape and the enzyme doesn’t change shape

24
Q

what are enzymes

A

biological catalysts

25
Q

how do enzymes accelerate rates of reaction

A

Lower activation energy by providing a lower energy pathway, a more favourable pH in the active site
using charge to put strain in bonds to break them
bring reactants together by using charge so that bonds form more easily

26
Q

what types of proteins are enzymes

A

globular

27
Q

what are intracellular enzymes

A

enzymes that work inside the cell
e.g. DNA polymerase

28
Q

what are extracellular enzymes

A

enzymes that work outside the cell
e.g. digestive enzymes

29
Q

Explain Lock and Key Theory

A
  1. Random movement causes enzyme and substrate to collide and the substrate enters the active site.
  2. Enzyme-substrate complex forms = shared groups attract, distort the substrate and aid in bond breaking/formation
  3. Products are released from active site, leaving it undamaged and ready to accept a new substrate
30
Q

what does structure of a protein determine

A

its function

30
Q

what type of protein is haemoglobin

A

globular

30
Q

what type of protein is collagen

A

fibrous

31
Q

describe structure of haemoglobin

A

globular with 4 polypeptide chains -2 alpha and 2 beta - each containing a haem prosthetic group

31
Q

what 2 types of secondary structure are there

A

alpha helix or beta pleated sheet

31
Q

describe the structure of collagen

A

fibrous with 3 polypeptides - 2 alpha and 1 beta

32
Q

how is a tertiary structure of a protein created

A

alpha helix / beta pleated sheet fold further and create a new structure held together by disulphide bridges and ionic bonds between R groups

32
Q

how is the quaternary structure of a protein created

A

folded polypeptides joined by hydrogen bonds - disulphide bridges and ionic binds between R groups

32
Q

what is the general formula for an amino acid

A

a central carbon, a hydrogen, an amine group (NH2) and a carboxylic acid (COOH)

33
Q

how are peptide bonds created

A

the OH in the carboxyl joins the H in another amino acid in a condensation reaction to remove water and form peptide bonds

34
Q

what is the primary structure of a protein

A

sequence of amino acids

35
Q

how does secondary structure of a protein formed

A

amino and carboxyl groups carry small amounts of charge
charge is negative on the CO and positive on the NH
result in H bonds forming between parts of the chain to stabilize the structure - alpha helix and beta pleated sheet

SNAB Biology Edexcel (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions