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bio > 3.4 Genetic info, variation + relationships > Flashcards

3.4 Genetic info, variation + relationships Flashcards

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1
Q

how is DNA stored in euk

A

euk-long, linear, associated with histone proteins

tightly coiled into chromosomes

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2
Q

how is DNA stored in prok

A

short
circular
not associated with proteins
free floating in cytoplasm

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3
Q

define gene

A 
sequence of DNA bases
that code for 
-amino acid sequence of polypeptide 
-functional RNA
occupies fixed position, called a locus
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4
Q

nature of genetic code

A

universal
-same DNA triplet codes for same amino acids in all organisms
non-overlapping
-each base read only once in one triplet
degenerate
-same amino acid can be coded for by more than one base triplet q

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5
Q

define genome

A

complete set of genes in a cell

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6
Q

define proteome

A

full range of proteins cell is able to produce

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7
Q

define allele

A

different version of same gene

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8
Q

similiarities + differences of mRNA and tRNA

A

similarities
-both single polynucleotide strand

differences

  • mRNA single helix/tRNA folded into clover shape
  • mRNA longer/tRNA shorter
  • mRNA no paired bases/H bonds / tRNA has some paired bases + H bonds
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9
Q

describe transcription

A

in nucleus
DNA double helix unzipped by DNA helicase
H bonds broken
free floating RNA nucleotides allign to complementary base on template strand
forming H bonds
RNA polymerase joins adjacent nucleotides-condensation reaction
forms phosphodiester bonds
RNA polymerase reaches STOP codon, detaches from DNA
-splicing
mRN leaves nucleus via nuclear pores

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10
Q

describe translation

A

sequence of mRNA codons determines sequence of amino acids
tRNA carry specific amino acids in relation to their amino acids
at ribosome tRNA codon binds to complementary mRNA codon
H bonds form
two amino acids join via condensation reaction
tRNA detaches, ribosome moves along mRNA
till stop codon

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11
Q

role of ATP in translation

A

hydrolysis of ATP releases energy
to form bond between amino acid + tRNA molecule
to form peptide bond between two amino acids

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12
Q

define gene mutation

A

change in base sequence of chromosomes
arise spontaneously during DNA replication
involve base deletion/substitution

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13
Q

how can a mutation lead to a non-functional protein

A
  • change in base sequence of DNA
  • changes sequence of mRNA
  • changes sequence of amino acids
  • changes position of bonds
  • changes tertiary structure
  • substrate cant bind
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14
Q

define mutagenic agent

A

increase rate of gene mutation

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15
Q

describe the process of meiosis

A

Meiosis I - seperates homologous pairs

  • chromosomes arrange into homologous pairs
  • cross over
  • independent segregation

Meiosis II -seperates chromatids

  • creates 4 haploid cells
  • genetically varied
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16
Q

how does meiosis create genetic variation

A

crossing over between homologous chromsomes

  • alleles exchanged between chromosomes
  • creates new combination

independent segregation of homologous chromosomes
-random allignment of homologous pairs at equator
creates different combinations

random fertilisation

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17
Q

importance of meisosis

A
  • two divisions- creates haploid gametes
  • diploid no restored at fertilisation
  • maintains chromsomes from one gen to the next
  • genetic variation
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18
Q

describe chromsome non-disjuncyion

A
  • homologous chromosomes/sister chromatids fail to seperate
  • during anaphase
  • both chromosomes/chromatids go to one pole of spindle
19
Q

formula to calulcate no of different combinations of chromosomes

A

2^n

20
Q

no of different combinations of chromsomes following random fertilisation of two gametes
(

A

(2^n)^n

21
Q

define genetic diversity

A

no. of different alleles in a population

22
Q

define population

A

group of interbreeding individuals of same species

23
Q

how does natural selection lead to evolution

A
  1. variation of alleles due to random DNA mutations
  2. selection pressure
  3. advantageous allele–>increased chance of survival + reproduction
  4. survive–>pass on advantageous allele to offspring
  5. frequency of advantageous allele increases in population over time/many generations
24
Q

define evolution

A

change in allele frequency over time

25
Q

describe directional selection

A

change to environment
selection pressures acts one side of mean
one extreme phenotype more likely to survive + produce
mean phenotype changes

26
Q

describe stabilising selection

A

stable environment
selection pressure acts on either side of mean
both extremes of phenotype less likely to survive + reproduce
mean phenotype remains the same

27
Q

define species

A

-two organisms of same species able to produce fertile offspring

28
Q

why is courtship behaviour needed in species recognition

A
  • species specificn
  • indication of sexual maturity
  • recognition of opposite sex
  • stimulates release of gametes
  • establishes pair bond
  • synchronised mating
29
Q

define phylogenetic classification system

A

arranges species based on evolutionary origins

30
Q

define hierarchy

A
  • smaller groups placed within larger groups

- no overlaps between each group

31
Q

order of hierarchy

A 
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
32
Q

what is genome sequencing

A

compare order of base sequence of whole genome of diff species
-higher match =more closely related

33
Q

what is immunology

A

DNA->mRNA->sequence of amino acids in polypeptide

same antibody binds to specific antigen = closely related

34
Q

define biodiversity

A

variety of living organisms in an area

35
Q

define species diversity

A

no. of different species + no. of individuals of each species within a community

36
Q

define community

A

all the populations of different species

in a habitat

37
Q

define index of diversity

A

describes relationship between no. of species in a community
+ no of individuals in each species

38
Q

farming techniques that reduce biodiversity

A
  • removal of woodland + hedgerows
  • monoculture
  • use of pesticides/herbicides/inorganic fertilisers
  • competition
39
Q

balance between conservation + farmin

A
  • use crop rotation of nitrogen fixing crops instead of fertilisers
  • maintain exisiting hedgerows + plant new hedges
  • reduce use of pesticides
40
Q

define continuous variation

A

no distinct categories
quantitative data
controlled by many genes
strongly influenced by height

41
Q

define discontinuous variation

A

distinct,discrete categories
qualitative data
controlled by a single gene
unaffected/not strongly influenced by environment

42
Q

how can genetic diversity be made between or within species

A

by measuring

  • the frequency of measurable or observable characteristics
  • the base sequence of DNA
  • the base sequence of mRNA
  • the amino acid sequence of the proteins encoded by DNA and mRNA.
43
Q

what is limited by looking at frequency of measurable characteristics

A
  • many observable characteristics coded for by more than one gene->vary continnously->difficult to distinguish from each other
  • characterisitcs could be modified by environment
44
Q

how to take a representative sample

A

random sample-eliminates bias
large sample
-minimises effect of chance
-anomalies have less influence + can be identified

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