Brainscape's Knowledge GenomeTM

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


See full index

HL Biology - topical sets > Topic 3 > Flashcards

Topic 3 Flashcards

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

how many genes were mapped as a part of the human genome project

A

25,000

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

Explain used a named example, how polygenic inheritance gives rise to continuous variation [4]

A
  • skin colour controlled by three or more genes
  • alleles are co-dominant
  • skin colour/amount of melanin a product of the cumulative effect of all the genes
  • human skin colour can vary from v light to v dark
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Explain the potential causes of Down syndrome [5]

A
  • Chromosome non-disjunction
  • can occur in anaphase 1 or 2
  • HOMOLOGOUS chromosomes fail to separate
  • one gamete receives 2 of the chromosomes
  • resultant fertilised gamete will have one extra chromosome
  • common form -> trisomy 21
  • increased risk w increased age of mother
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does therapeutic cloning involve

A

producing ESCs for medical use

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

Explain how DNA is used to pass on genetic information accurately but also produce variation within the species [8]

A
  • DNA rep is semi-conservative
  • mutations can cause genetic variation -> code for proteins w different functions
  • base substitution -> new alleles formed
  • sometimes mutations do not have actual effect on phenotype as no change to AA sequence
  • meiosis
  • crossing over
  • of linked genes (on same chromo) to produce new gene combinations -> RECOMBINES LINKED ALLELES
  • large variety of different haploid gametes an form
  • due to random orientation of bivalents in P1
  • random fertilisation
  • combining alleles of 2 different parents -> in SR
  • various phenotypes exist among the same population
  • genes occur as paired alleles which can be different
  • nat sel may lead to enhanced survival of recombinants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Explain the causes and consequences of sickle cell anaemia (from bioninja)

A
  • it is a base substitution mutation
  • CUC -> CAC on the template (antisense) strand, GAG -> GTG on the sense strand
  • mRNA changes from GAG-> GUG on the 6th codon position
  • codes for glutamic acid -> valine
  • 3d structure of haemoglobin affected -> forms insoluble fibrous strands
  • insoluble haemo can’t bind to O as effectively -> tiredness
  • RBC has a sickle instead of biconcave shape
  • easier to form clots as sickle cells can pack together easily
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Outline the outcomes of the human genome project [6]

A
  • promote international cooperation
  • provide evidence for evolutionary relationships
  • improve ability to SCREEN FOR certain diseases/ find genes causing certain diseases
  • tailor medication to individual genetic variation
  • development of new gene therapies
  • find the functions/structures of certain proteins
  • all the human genes/their positions mapped
  • complete human DNA SEQUENCED
  • find mutations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Distinguish between unique and highly repetitive DNA sequences [6]

A
  • HR makes up a larger proportion of the total genome than unique
  • unique are much shorter sequences than HR
  • unique are translated into proteins, HR aren’t
  • unique don’t vary much between individuals, HR vary highly
  • unique occur once in a genome, HR occur many times
  • unique may be genes, HR are not genes
  • repetitive DNA is used for profiling
  • satellite DNA is formed from repetitive sequences
  • prokaryotes usually don’t have repetitive sequences
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are the number of genes in a genome usually identified

A

by identifying gene sequences common to genes (eg - express sequence tags or sequences homologous to knwoen genes)
- however presence of pseudogenes and transposons makes this difficult

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

eukaryotic v prokaryotic dna (not the ms of a ppq)

A

e: histone bound p: naked
e: linear p: circular
e: in nucleus p: in cytoplasm
e: no plasmids p: plasmids
e: multiple molecules/chromosomes p: 1 dna molecule

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

eukaryotic dna packaging in chromosomes

A
  • octamer formed with 8 histones and DNA wrapped around
  • nucleosomes linked by additional protein -> form a string of chromatosomes
  • coil into a solenoid structure -> condensed into a fibre
  • fibre forms loops -> compressed around protein scaffold to form chromatin
  • chromatin supercoils into chromosomes in division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

how genes are identified on chromosomes

A

3 reference points:
- chromo number
- chromo arm (p or q) (p=shorter)
- the coordinate of the band

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

Y chromosome

A
  • has SRY gene -> to codes for the TDF (testis determining factor) -> causes embryonic gonads to become male gonads (testes)
  • w/o SRY gene –> female gonads (ovaries) form
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define karyotype

A

the number and types of chromosomes in a cell

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

How are karyotypes generated

A
  • cells harvested from blood/tissue/amniotic fluid
  • mitosis chemically induced
  • mitosis arrested in a stage where chromosomes visible
  • chromosomes stained and photographed to form a graph called karyogram
  • the chromo are arranged in homologous pairs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Autoradiography technique

A
  • Cells cultures in radioactive tritiated thymidine -> inc into cells
  • cells lysed -> isolate the chromosomes
  • chromosomes on photo paper –> immersed in radio-sensitive AgBr solution
  • AgBr grains form due to radiation of thymidine
  • excess agbr washed away -> silver grains appear as black dots on the film
  • photographic film developed -> dna can be visualised

Benefits results:
- can measure DNA molecule length when not supercoiled in mitosis
- showed formation of bidirectional replication in prokaryotes
- showed formation of replication bubbles in prokaryotes
- if tritiated uracil used –> it can be used to identify regions of active transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

which two factors aren’t valid indicators of organism complexity

A
  • genome size
  • chromosome number
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Generic trends for sizes of genomes

A
  • viruses and bacteria have small chrom no.
  • eukaryotes > prokaryotes
  • plants vary greatly –> polyploidy can occur
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Define karyotyping [1] (bioninja, not PPQ)

A

the process by which chromosomes are organised and visualised for inspection

20
Q

Describe amniocentesis [3]

A
  • amniotic fluid sample extracted w a needle
  • ~ at 16 weeks of prego
  • less risky than CVS
21
Q

Chorionic villus sampling

A
  • sample of chorionic villus extracted via tube through cervix
  • ~ 11 weeks
  • more risky -> risk of miscarriage
22
Q

Describe Mendel’s experiments and the conclusions drawn [7]

A
  • Mendel crossed different varieties of purebred plants
  • crossed the F1 generation with each other
  • saw that the when diff purebred varieties crossed, offspring not a blend
  • F2 gen would have both traits in a ratio 3:1

concluded that:
- specific traits determined by specific genes (‘discrete factors’
- two variations for each gene (alleles)
- dominant alleles always expressed if present
- as a result of fusion of nucleus, each parent contributes equally to inheritance of different traits
- each gamete has only one copy of an allele

Laws:
- Law of Independent assortment: The segregation of alleles for one gene occurs independently to that of any other gene (except linked genes)
- Principal of dominance: dominant alleles always expressed if present (co-dominance and incomplete dominance in some genes -> exception)
- Law od segregation: when gametes form -> alleles separated so each gamete carries only one

23
Q

Define genotype (bioninja) [1]

A

The gene composition of a particular trait

24
Q

Define phenotype [1] (bn)

A

the observable characteristics of a specific trait

25
Q

Describe the inheritance of ABO blood groups in humans [5]

A
  • The Ia and Ib alleles are dominant while the i allele is recessive
  • BT A: IaIa or Iai –> homozygous and heterozygous resp. /BT B: IbIb or Ibi –> homoz. and heteroz. resp. and BT O: only when there is a homoz. recessive phenotype: ii
  • BT AB: result of co-dominant alleles IaIb -> heteroz.
  • i, Ia and Ib are alleles
  • One allele inherited from each parent
26
Q

Give examples of autosomal recessive, autosomal dominant and co-dominant diseases

A
  • genetic diseases caused by mutations which can abrogate normal cell function -> causing disease phenotype
  • AR: CF
  • AD: Huntington’s
  • Co-dom: sickle cell anemia (only one copy of allele needed, but the individual will have milder symptoms if only 1 copy inherited)
27
Q

Describe the inheritance and the disease CF [4]

A
  • caused by mutation of CFTR gene, chromo. 7
  • autosomal recessive disease
  • excess mucus clogs airways, creating difficulty breathing and pancreatic cysts
  • if only 1 allele –> carrier
28
Q

Describe the inheritance and disease Huntington’s [5]

A
  • gene mutation on the Huntingtin (HTT) gene on chromo 4
  • autosomal dominant
  • causes by an excessive number of repeats of the CAG sequence
  • > 28 repeats is unstable -> sequence amplifies even more. once the number of repeats crosses 40 -> the huntingtin protein misfolds and causes neurodegeneration
  • symptoms develop in middle age
    causes uncontrollable spasodic movements + dementia
29
Q

Describe haemophilia - causes and effects [4]

A
  • X-linked recessive
  • more common in males (as a result)
  • coagulation factors for coagulation cascade are on X chromo -> mutation causes defect
  • fibrin doesn’t form properly
  • clotting impaired
30
Q

Describe red-green colour blindness [3]

A
  • patients cannot differentiate between red and green hues
  • mutation on the allele on the X chromo
  • affects red and green retinal photoreceptor cells
31
Q

Consequences of chernobyl and hiroshima

A
  • thyroid defects as high amounts of radioactive iodine
  • cancer frequency increased
  • in C particularly, increased amounts of birth defects
  • organ-specific abnormalities
  • Reduced t cell counts –> immune defects
  • some flora fauna variation also occurred
  • radiation accumulates in the ecosystem through bioaccumulation
32
Q

Describe the process of PCR [4]

A
  • Denaturation: DNA is heated to 95C (1min) to ensure the 2 strands of DNA separate
  • Annealing: DNA primers attach to the 3’ end (55C for 1 min)
  • Elongation: Taq polymerase (from thermophiles) bind to primer and are used at high temperatures (72C, 2 min) to rapidly replicate the DNA strands
33
Q

What is gel electrophoresis

A

when dna/protein fragments are placed on a block of gel + a current is run through it –> separating them by mass/fragment size
- smaller samples less impeded by gel matrix and travel further
- diff size -> separate

34
Q

GE for DNA process [5]

A
  • DNA cut at specific points using specific restriction endonucleases
  • negative charge on DNA (bc phosphate group) so fragments separate
  • frag placed on agarose gel, current run through it -> move negative to positive direction
  • those frag that travel faster/further -> smaller
  • compared against industry standards
35
Q

GE for protein process [4]

A
  • proteins come in a variety of sizes and don’t have a clear charge
  • treated which an anionic detergent -> uniform negative charge and linearised
  • put in polyacrylamide gel and current run through -> compared to industry standards
36
Q

Distinguish between unique and highly repetitive DNA sequences [6]

A
  • HR makes up a larger proportion of the total genome than unique
  • unique are much shorter sequences than HR
  • unique are translated into proteins, HR aren’t
  • unique don’t vary much between individuals, HR vary highly
  • unique occur once in a genome, HR occur many times
  • unique may be genes, HR are not genes
  • repetitive DNA is used for profiling
  • satellite DNA is formed from repetitive sequences
  • prokaryotes usually don’t have repetitive sequences
37
Q

Outline the outcomes of the human genome project [6]

A
  • promote international cooperation
  • provide evidence for evolutionary relationships
  • improve ability to SCREEN FOR certain diseases/ find genes causing certain diseases
  • tailor medication to individual genetic variation
  • development of new gene therapies
  • find the functions/structures of certain proteins
  • all the human genes/their positions mapped
  • complete human DNA SEQUENCED
  • find mutations
38
Q

Explain the methods and aims of DNA profiling [8]

A

Methods:
- DNA obtained from blood/hair/semen
- PCR to amplify the quantity
- satellite dna used
- Satellite DNA cut into fragments at specific points using restriction endonucleases
- different people have different lengths of STRs so the lengths of the fragments will differ
- gel electrophoresis of the fragments –> smaller sizes -> move faster so further
- number of repeats varies between individuals

Aims:
- Paternity test
- biological father if half of the bands produced are found in the father
- forensic investigation
- to compare the crime scene dna to suspect’s
- DNA profile must be complete match of the suspect’s

39
Q

Outline the basic process of gene transfer [6]

A
  • plasmid isolated from bacteria
  • plasmid cut open using specific restriction endonucleases
  • DNA isolated from an organism
  • gene of interest isolated via cutting with SAME restriction endonucleases
  • endonucleases create complementary sticky ends (CBP) on the plasmid and the gene of interest -> often 2 diff endo -> ensure the orientation of gene inserting is right and the plasmid doesn’t re-anneal
  • the backbone is spliced together using DNA ligase -> phosphodiester bond formed - recombinant plasmid
  • plasmid inserted into the host cell (recombinant organism)
40
Q

Using a named example, describe the benefits and disadvantages of GMO [9]

A
  • genetic modofocation is when the DNA/genotype of an organism is altered artificially
  • GM alters some phenotype of the organism
  • ex - Bt corn (gene from bacillus thuringiensis is inserted into corn –> insecticidal proeprties)

Benefits:
- Bt reduces need for chemical pesticides -> lower env risk
- GMO allows crops to be grown where otherwise it cannot be grown (eg salt tolerant tomatoes)
- may increase yield hence economic profit for farmers
- reduces need for rainforests to be cleared to grow crops
- provides more food
- lowered production costs

Harmful:
- May have impact on non-target organisms -> Bt corn pollen may be toxic to monarch butterfly caterpillars
- may impact food chain
- people may have reactions to the new food (allergic)
- some farmers may not be able to compete (small scale farmers)
- risk of cross pollination
- risk of long term soil contamination
- long term risks unknown

41
Q

Describe how scnt works [5]

A
  • egg cell isolated from host organism (host cell)
  • somatic cell isolated from donor organism
  • haploid nucleus of egg cell is removed
  • diploid nucleus of the somatic cell is removed and fused with the enucleated egg cell
  • electric current provided -> stimulate egg to divide into embryo
  • embryo re-inserted into the uterus of host organism -> clone of donor is created
42
Q

Describe natural methods of cloning

A

Through asexual reproduction:
- vegetative propagation (plants - as they have meristematic tissue) –> tubers, bulbs, runners)
- spores: fungi and some plants
- Budding: hydra
- binary fission: planaria
- fragmentation: starfish
- parthenogenesis -> the offspring form from unfertilised ova (some insect/fish species)

Through sexual reproduction:
- identical twins –> the zygote splits into 2 after fertilisation (monozygotic)
- fraternal -> unfertilised egg splits into 2 -> 50% DNA is same (dizygotic)

43
Q

Artificial cloning methods

A
  • SCNT -> traits can be controlled
    or
  • separating the cells of an embryo in lab when embryo is in 8-cell stage (morula)
  • embryo pluripotent –> each cell dev into a new organism
  • clones of the original embryo formed
  • though traits cant be controlled as fertilisation still occurs randomly
44
Q

How stem cuttings work and influencing factors

A
  • all plant stems are divided into nodes -> between nodes are internodes
  • leaves/roots/aerial roots grow from nodes
  • cuttings placed in soil with lower nodes covered, and upper exposed
  • to rapidly propagate plants

growth dependent on:
- growth hormones
- temperature
- length of node from cutting (cutting position)
- water avail
- growth medium
- cutting length

45
Q

Explain Cairns’ technique to measure DNA molecule length [2] (a MSYK from PPQ MS)

A
  • Grew E coli in radioactive thymidine
  • put contents of the cell on photographic film paper
  • measured the length of the DNA molecule and photographed it
  • could show new strands were all labelled with thymidine

HL Biology - topical sets (11 decks)

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