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biology > Topic 2~ Genes And Health > Flashcards

Topic 2~ Genes And Health Flashcards

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AP® Biology flashcards
1
Q

What type of cell produces mucus

A

Goblet cells

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2
Q

What are the properties of gas exchange surfaces

A
  • large surface area : volume
  • good blood supply
  • thin walls
  • concentration gradient (greater the better)
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3
Q

Ficks law

A

Rate of diffusion is directly proportional to

SA x difference in conc / thickness

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4
Q

Structure of an amino acid

A

Central carbon is bonded to an anime group (NH2) opposite a carboxylic acid group (COOH) and a hydrogen (H) opposite an R group

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5
Q

What is the primary structure of a protein

A

The sequence of amino acids in a polypeptide chains

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6
Q

Formation of a dipeptide

A

2 amino acids join by peptide bonds by a condensation reaction

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7
Q

What is the secondary structure of a protein

A

Polypeptide chains twist or fold to form a-helix or b-pleated sheets with hydrogen bonding between C=O and NH

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8
Q

What is the tertiary structure of a protein

A

Polypeptide chain bends and folds further into a precise 3-dimensional shape. Ionic bonds and disulphide bridges form

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9
Q

What is the quaternary structure of a protein

A

Multiple polypeptide chains held together

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10
Q

What are conjugated proteins

A

Proteins that have another chemical group associated with their polypeptide chain
Like haemoglobin is associated with iron

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11
Q

What are globular proteins + examples

A

The polypeptide chain is folded into compact spherical shape
Roles in binding to other substances

Haemoglobin
Enzymes
Antibodies

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12
Q

What are fibrous proteins + examples

A

Do not fold into a sphere but instead remain as long chains. Have cross linkage between chains for strength
Important structural molecules

Keratin
Collagen
Tendons

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13
Q

Structure of haemoglobin

A

Globular protein
conjugated protein
Made up of 4 polypeptide chains
Each associated with iron haem group

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14
Q

Structure of collagen

A

Fibrous protein
Made up of 3 polypeptide chains wind around each other forming triple helix (rope like)
Held by hydrogen bonds
Each stand cross links to other stands
Strands are staggered to avoid weak points

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15
Q

What are peripheral proteins

A

Proteins that are attached on the outside surface of the cell membrane

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16
Q

What are integral proteins

A

Proteins that are fully embedded within the phospholipid bilayer

They have regions of polar hydrophilic amino acids at the ends and non polar hydrophobic amino acids in the middle portion

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17
Q

How can the phospholipid bilayer become more fluid

A

With a greater ratio of unsaturated to saturated fatty acids

The kinks prevent them from packing closely together so more movement is possible

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18
Q

What is facilitated diffusion

A

Diffusion across the membrane with the aid of proteins for polar molecules and ions

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19
Q

What are channel proteins

A

They are proteins that span the membrane and allow polar molecules and ions to diffuse through

Each type has a specific shape that permits the passage of a particular ion or molecule

Some are opened and closed depending on the presence or absence of a signal, like a hormone

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20
Q

What are carrier proteins

A

Proteins in the membrane that transport polar molecules or ions.

The ion or molecule bonds onto a specific site on the protein causing it to change shape. As a result the ion or molecule crosses the membrane

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21
Q

Why is diffusion sometimes called passive transport

A

Because no metabolic energy is needed for the transport - it’s driven by the concentration gradient

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22
Q

Definition of osmosis

A

The net movement of water molecules from a solution with high concentration of water (low solute conc) to a low concentration of water (high solute conc) through a partially permeable membrane

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23
Q

Definition of isotonic

A

Equilibrium

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24
Q

Describe the process of active transport

A

Movement of substances from low to high concentration
Requires carrier proteins and ATP
- Substance binds to the carrier protein
- 1 phosphate group is removed from ATP by hydrolysis forming ADP and inorganic phosphate
- phosphate gets hydrated, lots of energy released as bonds form between water and phosphate changing shape of carrier protein
- substance released on other side

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25
Q

What is exocytosis

A

Release of substances from the cell as vesicles fuse with the cell membrane releasing the contents

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26
Q

What is endocytosis

A

Substances are taken into cell by creation of a vehicle from the cell surface membrane - part of the membrane engulfs the substance

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27
Q

What happens when there is too much water in mucus of lungs

A
  • sodium is actively pumped out of cells into tissue fluid, reducing sodium conc in the cell
  • sodium then diffuses out of mucus and into cells
  • chloride diffuses down electrical gradient
  • water is drawn out of the cells by osmosis due to high salt conc in tissue fluid
  • water is then drawn out of the mucus by osmosis
28
Q

What happens when there is too little water in the mucus of the lungs

A
  • chloride is pumped into the cell from tissue fluid
  • chloride diffuses through the open CFTR channel in mucus
  • sodium diffuses down electrical gradient into the mucus
  • increased salt conc in mucus draws water out of the cell by osmosis
  • water is drawn into the cell from the tissue fluid by osmosis
29
Q

Why can’t Cystic fibrosis lungs regulate water in the mucus

A
  • the CFTR protein is missing or not working
  • so chloride ions cannot be transported into the mucus when it’s too sticky
  • sodium channels are still open allowing more sodium ions to diffuses out of the mucus
  • more water is drawn out of mucus
  • even stickier
30
Q

Describe the lock and key theory

A
  • substrate molecule has a complementary shape to the active site
  • form temporary bonds with the active site to produce enzyme-substrate complex
  • products are then released leaving enzyme unchanged
  • each enzyme will catalyses one specific reaction as only one shape of substrate fits precisely to active site
31
Q

Describe the induced fit theory

A
  • active site is flexible
  • when the substrate enters the active site, enzyme changes shape slightly to fit mire closely around substrate
  • only specifically shaped substrate will induce the correct change in shape of enzymes active site
32
Q

How do enzymes reduce the activation energy

A

Electrically charged groups on surface of active site and substrate interact
Attraction of oppositely charged groups distorts the shape of the substrate assisting in breaking or forming bonds

33
Q

Definition of metabolism

A

The sum of all the enzyme catalysed reactions occurring within an organism

34
Q

What are intercellular enzymes

A

enzymes that catalyse reactions inside cells

35
Q

What are extracellular enzymes

A

Enzymes that catalyse reactions outside cells

36
Q

What is a gene

A

Sequence of bases on a DNA molecule that codes for a sequence of amino acids

37
Q

What is the genome

A

All the genes in an individual

38
Q

What are the monomers of DNA

A

Nucleotides

39
Q

What’s the structure of a nucleotide

A

Deoxyribose sugar, a phosphate group and an organic nitrogenous base linked by condensation reactions

40
Q

How do nucleotides join together

A

Condensation reactions between the sugar and phosphate forming a phosphodiester bond

41
Q

Why do the bases pair up

A
  • A, G have 2 ring structure
  • T, C have 1 ring structure

Each ‘ring’ of DNA has 3 rings

  • shape and chemical structure dictates how many hydrogen bonds each one can form, determining the pairing
42
Q

What is the difference between DNA and RNA

A
  • RNA is single stranded
  • RNA is made of RNA nucleotides (contain ribose sugar instead of deoxyribose)
  • RNA has uracil instead of thymine
43
Q

Describe the process of transcription

A
  • DNA unwinds by breaking hydrogen bonds
  • template strand is transcribed using free RNA nucleotides, DNA polymerase and complementary base pairing to form an mRNA molecule
  • mRNA leaves nucleus through pore in the nuclear envelope and DNA ‘zips up’
44
Q

Which strand is the antisense strand

A

Template strand

45
Q

Describe the nature of the genetic code

A
  • code carried by DNA in triplets
  • non-overlapping (each base read once)
  • degenerate (several triplets code for same amino acid)
46
Q

Describe the process of translation

A
  • mRNA attaches to a ribosome
  • tRNA anticodon hydrogen bonds to complementary codon on mRNA for a particular amino acid
  • ribosome holds it all in place while peptide bond forms between amino acids by condensation reactions
47
Q

Where are ribosomes found

A
  • free in cytoplasm

- attached to endoplasmic reticulum

48
Q

How do stop codons work

A

There are no tRNA molecules with complementary anticodons to stop codon sequences so no amino acid can be transferred.

The polypeptide chain stops growing and detached from the ribosome

49
Q

Compare DNA replication and transcription

A
  • both create new molecule of nucleic acids
  • both make copies of DNA
  • transcription copies DNA into RNA while replication makes another DNA
  • transcription is for gene expression while replication is for cell division
  • transcription uses RNA nucleotides and replication uses DNA nucleotides
  • transcription unwinds part of DNA but replication unwinds entire DNA
50
Q

Describe DNA replication

A
  • hydrogen bonds between bases break making DNA unzip
  • DNA nucleotides pair up with complementary bases
  • DNA polymerase links adjacent nucleotides
  • 2 identical daughter strands created
51
Q

Describe Meselson and Stahls experiment for DNA replication

A
  • grew Bacteria in a medium with heavy isotope of nitrogen
  • moved bacteria into medium with lighter nitrogen
  • extracted and centrifuged DNA
  • after 1 replication only 1 band formed showing medium dentistry (heavy + light)
  • after 2 replications 2 bands formed showing medium density and light density
  • proves semi conservative replication
52
Q

Definition of locus

A

The position of a gene on a chromosome

53
Q

Definition of homologous chromosomes

A

Chromosome pairs inherited from each parent

54
Q

Definition of allele

A

Alternative forms of the same gene

55
Q

Definition of genotype

A

Alleles a person has

56
Q

Definition of homozygous genotype

A

Identical alleles

57
Q

Definition of heterozygous genotype

A

Different alleles

58
Q

Definition of phenotype

A

Characteristics of the organism caused by the genotype

59
Q

Definition of monohybrid inheritance

A

Characteristic controlled by only one gene

60
Q

Definition of incomplete dominance

A

Neither allele is dominant so heterozygotes have an intermediate phenotype

61
Q

How can genetic screening be used

A
  • to confirm diagnosis
  • to identify carriers
  • for testing embryos
62
Q

What is amniocentesis

A

Common method of prenatal testing

Involves inserting a needle into amniotic fluid to collect fetal cells that have fallen off the placenta

63
Q

What is chorionic villus sampling

A

Method of prenatal testing

Small sample of placental tissue is removed through abdomen wall or vagina

64
Q

What are the implications of prenatal genetic screening

A
  • both procedures present risk of miscarriage
65
Q

What is non-invasive prenatal diagnosis

A

Analysing DNA fragments in mothers blood plasma during pregnancy

66
Q

What is pre-implantation genetic diagnosis (PGD)

A

When a couple has family history of a serious genetic condition or already have a child with the condition they undergo IVF to create embryos that can be tested before transfer to the uterus

biology (7 decks)

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