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genes and health Flashcards

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1
Q

describe the role of tRNA

A

tRNA molecules transport amino acids to the ribosome. tRNA molecule has a complimenteray anticodon that binds to a codon on the mRNA. each tRNA carries a particular amino acid. tRNA binds to ribosome

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2
Q

compare and contrast the process of endocytosis and exotycosis

A
  • both processes involve vesicles and both involve energy/ATP
  • exocytosis involves substances leaving the cell whereas endocytosis involves substances entering the cell. exocytosis involve vesicles fusing with cell surface membrane whereas endocytosis involves the formation of vesicles
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3
Q

function of glycoprotein

A

cell recognition/receptors/antigens

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4
Q

explain how the structure of a phospholipid molecule contributes to the partial permeability of the membrane

A

contains hydrophilic phosphate head and hydrophobic fatty acid chains. it allows non-polar molecules to pass through the membrane. polar molecules cannot pass through the phospholipid bilayer

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5
Q

how do phopsholipids form bilayer

A

hydrophilic parts associate with water. hydrophobic parts repel with water. a bilayer forms with hydrophobic parts pointing towards the centre of the bilayer

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6
Q

why are phospholipids arranged into two layers in a membrane

A

hydrophilic region orientated towards water and hydrophobic regions away from the water (in the centre). solution either side of the cell membrane

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7
Q

function of carrier protein

A

involved in facilitated diffusion. movement of large molecules from a high to low concentration. involved in active transport.

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8
Q

describe the structure of the cell surface membrane

A

it is phospholipids and protein. phospholipids form a bilayer. proteins float in the phospholipids

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9
Q

how does primary sturcture of leptin allow it to be soluble

A

primary structure determines the folding of the polypeptide forming a globular structure. hydrophobic r groups are located in the centre of the protein. water forms hydrogen bonds with protein

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10
Q

how does substitution base affect fucntion of molecule

A

different triplet is produced which changes the codons in mRNA resulting in a different amino acid. but this may code for the same amino acid. due to the degenerate nature of the genetic code

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11
Q

why can enzymes that arent correctly folded not carry out its function

A

teriary structure would be different so active site of enzyme wouldn’t bind with the enzyme/wouldn’t be able to form enzyme susbtratwe complex. therefore, it wouldnot be able to catalyse the reaction

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12
Q

compare and contrast globular and fibrous proteins

A

both are chains of amino acids joined by peptide bonds. both contain hydrogen and ionic bonds, disulfide bridges.
globular proteins have hydophilic groups on the outside whereas fibrous proteins have little or no tertiary structure.
globular are folded into compact shapes whereas fibrous have long chains

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13
Q

how is a peptide bpnd formed

A

condensation reaction between amine group and carboxyl group of adjacent amino acids

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14
Q

products when several amino acids are joined toegther

A

water and polypeptide

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15
Q

compare transcription and DNA replication

A

both involve formation of polynucleotide. both involve DNA helicase. transcription uses RNA nucleotides and RNA polymerase whereas replication uses DNA nucleotides and DNA polymerase. transcription produces single strand of mRNA whereas replication produces double stranded DNA

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16
Q

what deos a frameshift do

A

changes triplet code so introduces a new coodn which codes for a shorter sequence of amino acids. more likely to affect the position of a start/stop coodn

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17
Q

describe how mRNA is synthesised at a template strand

A

RNA nucleotides align with complementary bases. RNA nuclepotides joined together by RNA polymerase/phosphodiester bonds

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18
Q

compare RNA and DNA

A

DNA is double stranded whereas RNA is single stranded. DNA contains deoxyribose while RNA contains ribose. DNA contains thymine whereas RNA contains uracil

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19
Q

which type of bond holds strands of dna together

A

hydorgen

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20
Q

describe how nucleotides join together to form dna

A

condensation reaction. phosphodiester bonds. DNA polymerase

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21
Q

why did they accept one of the dna replication models and not the otger

A

semi-conservatvie model was accepted because generation 1 has a single band which is halfway between 15N and one 14N. the dna has one strand containing 15N and one strand containing 14N. further generations would have a band halfway between 15N and 14N

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22
Q

why does antibiotics that binds to ribosome affect production of protein

A

mRNA is prevented from binding to the ribosome. so translation cant occur so protein can’t be synthesised

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23
Q

describe the role of CFTR in ensuring that mucus produced in the lungs is the right consistency

A

chloride ions leave the cell. sodium ions leave the cell. this increases the solute concentration in the mucus. water moves out of the cells and into mucus by osmosis

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24
Q

describe the roles of translation and transcription

A

the gene for the protein is transcribed. complementary base pairing between RNA nucleotides and DNA. mRNA leaves the nucleus and attaches to the ribosome. pairing between codons on mRNA and anticodons kn tRNA. tRNA provides specific asmino acids. the sequence of bases determione the primary structure

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25
explain why different mutations in the CFTRNgene can lead to differences in the severity of the symptoms of cystic fibrosis
different mutations will have different effects on the protein produced chloride ion transport affected by the extent of changes varying the stickiness of mucus
26
why does cystic fibrosis affect the rate of oxygen uptake in lungs
thick sticky mucus which cannot be moved by cilia restricting air flow trhough bronchioles reduced surface area for gas exchange in the alveoli
27
how many hydrogen bonds between a-t
2
28
how many hydrogen bonds between c-g
3
29
why do children with cystic fibrosis need dietary supplements and digestive enzymes
cystic fibrosis causes the production of stuckier thicker mucus this blocks the pancreatic duct which prevents pancreas / digestive enzymes from reaching the small intestines prevents enzymes from digesting in intestines resulting in reduced absorption of products of digestion / nutrients into the blood Mucus can cause cysts to form in pancreas digestive enzymes and dietary supplements would increase growth rate
30
what does CFTR gene code for
a channel protein
31
why may parents choose not to do CVS
Test result may be innacurate increased risk of miscarriage false positive may lead to termination of healthy fetus against values or beliefs of the parents
32
definition of inherited recessive disorder
caused by a faulty allele only expressed in the homozygous condition
33
what is it called when many different siblings are different genotype
incomplete dominance Both alleles expressed
34
allele definitin
alternative form of a gene found at the same locus
35
how to know if parents are heterozygous
if some of the children have the recessive disease
36
what is cvs
chorionic villus sampling cells taken from placenta between 10-14 weeks of pregnancy benefit of earlier diagnosis
37
amniocentesis definition
amniotic fluid containing cells collected betwen 14-20 weeks of pregnancy lower risk of miscarriage
38
horse can be either red or white but it is orange what happened?
heterozygous therefore incomplete codominance occurs because both alleles are expressed
39
advantage of genetic screening
prevents child dying late in pregnancy and parents can prepare for child. less stress for parents
40
difference between substitution and addition
loss causes frame shift replacement only changes one codon so number of amino acids remain the same
41
template
RNA nucleotides attach to this strand
42
what is pre implantation genetic diagnosis
an embryo created by IVF can be screened before it is placed in the mothers uterus
43
fluid mosaic meaning
fluid refers to the movement of the phospholipids in the plane of the membrane mosaic refers to the random association of proteins within the membrane
44
properites of cells that allow them to enter cells by diffusion
small, non-polar, lipid soluble
45
compare facilitated diffusion and active trasnsport
both transport molecles. hoewver active transport is against a concentration gradient while facilitated diffusion is down it. facilitated diffusion doesnt require ATP
46
how is channel protein involved in passive transport
allows movement of large molecles by diffusion down a concentration gradient
47
why do people with cf hage breathing difficulties
stickier thicker mucus blocking brocnhioles Cilia cant move it out of lungs reduced flow of air to alveoli reduced gaseous exchange loss of surace area redyuced concentration gradient trapped bacteria may result in more lung infectioons
48
recessive allele
different forms of a gene and both need ti be present in order for the recessive phenotype to be express
49
between bases
hydrogen bonds
50
Non overlapping
Base triplets don’t share their bases. These are seperate
51
Degenerate
More possible combinations of triplets than there are amino acids. One amino acid can be coded for by more than one base triplet
52
Mono hybrid inheritance
Inheritance of single characteristic determined by one gene with two alleles
53
Screening embryos for genetic disorders before they’re implanted in a woman
Preimplantation genetic diagnosis
54
explain why a fertilised egg cell will contain only maternal mitochondria
only nucleus of sperm enters ovum therefore all mitochondria comes from the egg cell
55
inheritance of parental characteristics in offspring
DNA in nucleus comes from sperm and egg of parents characteristics determined by DNA in nucleus is inherited by parents
56
Exaplin why stem cells from heart can’t be used to grow cells from cornea
Cells aren’t totipotent Some genes already activated/ deactivated Will not be able to specialise into cornea cells
57
Diffusion definition
Net movement of particles from an area of higher concentration to lower DOWN concentration gradient
58
How to increase ate of diffusion
- large sa:v ratio - thin - short diffusion distance - steep concentration gradient
59
Osmosis definition
Movement of free water molecules through a partially permeable membrane from an area of higher concentration of water molecules to an area of lower concentration
60
Difference between carrier protein and channel protein
Carrier protein: - moves large molecules into/out the cell, down concentration gradient - large molecule attaches to carrier protein in the membrane - protein changes shape - it releases the molecule on the opposite side of the membrane Channel protein: - form pores in membrane for charged particles to diffuse down conc gradient
61
Energy in active transport
- It acts as immediate source of energy in the cell - When ATP is hydrolysed, energy is released - this energy is used it move the molecule against its concentration gradient
62
How temperature affects membrane permeability
- as temperature increases, phospholipids move more becaus they have more energy so permeability increases - above 45 C, water in cell expands, putting pressure on the membrane. Channel and carrier proteins deform so they can’t control what leaves/enters cell so increased permeability of membrane
63
Dipeptide
Two amino acids
64
Primary structure
Sequence of amino acids in polypeptide chain
65
Secondary structure
Hydrogen bonds form between amino acids in chain. Makes alpha helix and beta pleated sheets
66
Quarternary structures
Proteins made of several different polypeptide chains held together by bonds. E.g. haemoglobin, insulin and collagen
67
Bonds in primary structure
Peptide
68
Bonds in secondary structure
Hydrogen
69
Bonds in tertiary structure
All: ionic, disulfide, hydrogen
70
Example of globular
Haemoglobin Soluble so easily transported Has iron containing haem groups that bind to oxygen
71
Example of fibrous protein
Collagen as is if strong and found in supportive tissue
72
Gene definition
Sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain
73
Enzymes definition
Speed up chemical reactions by acting as biological catalysts They reduce activation energy
74
Intracellular enzymes
Catalyse reactions inside cells
75
Extracellular enzymes
Produced by cells catalysing reactions outside of cells
76
What happens if enzyme has different tertiary structure
Different shaped active site Substrate can’t fit into active site Enzyme substrate complex won’t be formed
77
How substrate concentration affects rate of reaction
- faster reaction - more substrate molecules so collision between substrate and enzyme is more likely so more active sites used - when graph levels off, all active sites are full
77
How enzyme concentration changes rate of reaction
- More enzyme molecules means more active sites present - More likely a substrate molecule is to collide with an active site, forming an enzyme-substrate complex so rate of reaction increases - if substrate concentration becomes limiting factor, the graph levels off
78
Site of transcription
Nucleus
79
Site of translation
Cytoplasm
80
mRNA vs tRNA
mRNA: - made in nucleus during transcription - three adjacent bases are called a codon - carries genetic code from DNA in nucleus to cytoplasm tRNA: - found. In cytoplasm - has an amino acid binding site at one end and a sequence of three bases at the other end called anticodon - caries amino acids that are used to make proteins to ribosomes
81
Role of template strand in transcription
- when DNA unwinds, one of the strands is used as a template to make an mRNA copy - RNA polymerase lines up free RNA nucleotides alongside the template strand
82
Explain DNA replication
- DNA helicase breaks hydrogen bonds between bases on 2 DNA strands so it unwinds - complementary base pairing between free DNA nucleotides and complementary exposed bases on original template strand - condensation reactions join nucleotides, DNA polymerase. Hydrogen bonds form between bases on original and new strands - each new DNA molecule contains one strand from the original DNA molecule and one new strand
83
Explain meselson and stahl’s experiment DNA replication
84
Genotype meaning
alleles a person has
85
Phenotype meaning
Characteristics displayed by an organism
86
Dominant allele
Characteristic expressed in phenotype even when there’s only one copy
87
Homozygous
An organism that carries two copies of the same allele for a certain characteristic
88
Heterozygous
An organism that carries two different alleles for a certain characteristic
89
Mono hybrid inheritance
Inheritance of a single characteristic controlled by different alleles
90
Incomplete dominance
When trait is not completely expressed over the trait produced by recessive allele
91
Null hypothesis
No significant difference
92
How mucus in cystic fibrosis affect reproductive system
Sperm duct blocked by thick mucus so sperm can’t reach penis thickened cervical mucus can prevent soerm from reaching egg Sperm has reduced movement - lower chance of it reaching the egg
93
Identification of carriers
- offered to individuals with a family history of genetic disorders - allow people to make informed decisions, like keeping children and whether to carry out prenatal testing - may cause emotional stress - false results as they aren’t accurate - results could be used by employers or life insurance companies - resulting in generic discrimination
94
Pre implantation genetic diagnosis
- carried out on embryos produced by IN VITRO FERTILISATION - screening embryos for genetic disorders before they’ve implanted into the woman - performed before implantation, so avoids issue of abortion that could be raised by prenatal testing - reduces chance of having baby with genetic disorders as only embryos without them will be implanted - can find out other characteristics, like gender, eye colour, so embryos may be selected with specific characteristics

biology (11 decks)

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