Cellular Control

  • Protein synthesis
  • lac operon
  • homeobox genes
  • mutations
  • apoptosis
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  • Created by: Sarah
  • Created on: 14-02-15 10:07
Q: Two forms of nucleic acids
A: DNA and RNA
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Q: where is DNA found?
A: nucleus of EUKARYOTIC cells
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Q: nucleic acids consist of
A: phosphate, pentose sugar, nitrogenous base
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Q: structure of purines
A: double ring structure (DOUBLE = to make up for the shorter name&theres only TWO)
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Q: structure of pyrmidines
A: single ring structure
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Q: names of purines
A: Adenine(A) + Guanine(G)
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Q: names of pyrimidines
A: Thymine (T) + Cytosine(C) + Uracil (U)
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Q: does mRNA contain H bonds?
A: no
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Q: does tRNA contain H bonds?
A: yes
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Q: does DNA contain H bonds?
A: yes
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Q: does mRNA have exposed of paired bases?
A: exposed
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Q: does tRNA have exposed of paired bases?
A: exposed and paired
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Q: does DNA have exposed of paired bases?
A: paired
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Define: Protein
a polymer of many monomers of amino acids joined by peptide bonds in a condensation reaction
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Define: Gene
a length of DNA that codes for one or more polypeptide
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Define: Codon
a sequence of 3 bases of an mRNA molecule
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Define: Transcription
the first stage of protein synthesis where a sequence of bases on the coding strand of DNA are copied into a mRNA molecule
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Features of genetic code
triplet code / degenerative / almost universal / non-overlapping
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Q: first stage of protein synthesis
A: transcription
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A: mRNA is a copy of ________?
A: DNA coding strand
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Q: free RNA nucleotides are found in the ________?
A: nucleolus
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Q: why genetic code would not work if bases where in pairs instead of triplets?
A:
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Q: what part of the ribosome does mRNA attach to?
A: small sub-unit
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Q: how many codons are exposed in the large sub-unit of a ribosome at one time?
A: two
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Q: start codon is always
A: AUG
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Q: is protein synthesis faster in prokaryotes or eukaryotes? why?
A: fastest in prokaryotes (bacteria) as mRNA does not have to exit the nucleus / there are no histones as DNA is naked
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Q: minimum number of tRNA molecules needs for protein synthesis? why?
A: 21 - one for each amino acid + one stop codon
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Q: how are nucleotide chains of DNA bonded?
A: Two antiparallel chains / hydrogen bonds between them / complementary base pairing between purines and pyrimidines
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Q: how DNA structure determines protein shape
A: DNA codes for polypeptide / translation+transcription / sequence of triplet code = sequence of amino acids = specific primary structure / coils or pleats to form secondary structure / further coiling and pleating and bonding = tertiar 3-D structur
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Define: Enzyme induction
involves certain enzymes being synthesised due to environmental changes
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Q: what substrate does E.coil respire?
A: Glucose and Lactose
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Q: enzymes need for lactose respiration
A: B-galactosidase + lactose permease
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Q: role of B-galactosidase
A: lactose --> glactose + glucose
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Q: role of lactose permease
A: transport lactose into the bacterial cell
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Q: what is the lac operon
A: a section of DNA in a bacterium consisting of structural genes and control sites
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Define: inducilble enzymes
enzymes synthesised at varying rates depending of the environment
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Q: on the lac operon the Z structural gene codes for?
A: B-galactosidase
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Q: on the lac operon the Y structural gene codes for?
A: Lactose permease
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Q: function of structural genes
A: codes for lac enzymes
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Q: name of lac enzymes
A: Lactose permease + B-galactosidase
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Q: function of operator region
A: switches transcription of structural genes on and off
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Q: function of promoter region
A: where RNA polymerase binds to initiate transcription of structural genes
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Q: order of lac operon components?
A: promoter region / operator region / structural gene Z / structural gene Y (P/O/Z/Y)
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Q: function of regulatory gene
a gene that codes for a repressor protein
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Define: repressor protein
a protein that attaches to the OPERATOR region preventing RNA polymerase binding to the PROMOTER region to start transcription
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Q: on the lac operon, RNA polymerase binds to?
A: promoter region
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Q: on the lac operon the repressor protein binds to?
A: operator region
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Q: what is the role of lactose?
A: acts an inducer / binds to repressor / repressor dettaches from operator / RNA polymerase can attach to promoter region / genes transcribed
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Q: the advantage of E.coil having the lac operon
A: enzymes are inducible / resources not wasted making unnecessary enzymes
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Q: what type of macromolecule is a repressor protein?
A: protein
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Q: what happens at the lac operon if lactose is present?
A: lactose binds to repressor protein (inducer) / repressor changes shape / dettaches from operator / RNA polymerase attaches to promotor / transcription begins
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Q: where does the repressor protein bind to (on the lac operon)
A: operator region
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Q: why are B-galactosidase and lactose permease NOT produced where there is NO lactose
A: repressor bound to operator region / RNA polymerase cannot bind to promotor region to begin transcription
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Q: Lactose can be hydrolysed (broken down) into to
A: glucose + lactose
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Define: mutation
a change in the AMOUNT of or ARRANGEMENTS of genetic material within a cell
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Define: chromosome mutation
a change in part or whole of a chromosome following cell division
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Q: when would a chromosome mutation occur?
A: after cell division
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Define: DNA mutation
a change in gene resulting in a change of the nucleotide base sequence following DNA replication
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Q: when would a DNA mutation occur?
A: after DNA replication
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Q: what are the classes of DNA mutation?
A: point mutation (substitution) and frameshift (insertion/deletion)
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Define frameshift
a DNA mutation where by one of more nucleotide pair is inserted or deleted
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Define: point mutation
a DNA mutation where by one amino acid is replaced by another
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Q: classes of point mutations
A: missense mutation / nonsense mutation / silent mutation
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Define: missense mutation
a DNA point mutation where an amino acid is replaced by a DIFFERENT amino acid
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Define: nonsense mutation
a DNA point mutation where an amino acid is replaced by a STOP codon
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Define: silent mutation
a DNA point mutation where a change in nucleotide pair results in the same amino acid being coded for (due to degenerative genetic code)
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Q: how comes some mutations have neutral effects
A: silent=same amino acid coded for / occurs at a non-coding region of DNA / provides no advantage or disadvantage
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Define: Somatic cell
a normal cell containing the diploid number of chromosomes
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Q: are mutations in somatic cells inherited? and why?
A: no because they are not involved in the formation of gametes
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Q: what are mutagens
A: substances that disrupt DNA structure or interfere with transcription E.G. UV light/X-rays/tar
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Q: Examples of mutagens
UV Light (sunlight) / X-rays / tar (in tobacco)
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Q: type of mutation that causes cystic fibrosis
A: DNA deletion mutation / deletion of a triplet of base pairs
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Q: what is the effect of Cystic fibrosis mutation
disrupts chloride ion + water transport / cilia dehydrates / build up of mucus in gut, reproductive tract and airways
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Q: symptoms of cystic fibrosis
A: shortness of breath / fatigued / infection / inflammation / infertile
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Q: type of mutation that causes sickle cell anemia
A: DNA point mutation / one amino acid replaces another
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Q: type of mutation that causes huntingtons disease
A: repeated triplet code
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Q: type of mutation that causes tumours
A: mutation of growth promoting genes leading to excessive cell division
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Define: homebox genes
genes which act as transciption factors controlling the expression of genes important in the development of a body plan incl. polarity and organ positioning
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Define: Hox cluster
a cluster of homeobox genes
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Define: polarity
the head to tail of an organism
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Define: morphogen
a substance that governs tissue development
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Q: how can a morphogen affect a pregnant women
A: govern the tissue development of embryo / baby born with birth defects
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Define: Apoptosis
programmed cell death
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Q: what is the opposite of apoptosis?
necrosis
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Q: what the term for programmed cell death
A: Apoptosis
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Q: what is the term for disorderly/destructive cell death?
A: necrosis
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Q: when is necrosis likely to occur
A: after a traua/accident
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Q: what is the maximum number of miotic division a cell can undertake
A: 50
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Q: what is the term for the maximum number of times a cell can divide?
A: Hayflick constant
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Define: Hayflick constant
the maximum number of times a cell can divide (50)
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Q: what controls apoptosis?
A: cell signalling / cytokines/hormones/nitric oxide
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Q: insufficent apoptosis can lead to
A: tumours
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Q: too much apoptosis can lead to
A: cell loss or degeneration
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Q: function of apoptosis
A: tissue development (digits) / removal ineffective/harmful T-lymphocytes / recyling of cell components / protection of surrounding cells
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Q: how nitric oxide effects mitochondrial membrane
A: dissipates proton gradient / less ATP production
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Q: how does apoptosis not damage surrounding cells?
hydrochloric enzymes are enclosed in vesciles
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Q: characteristics of discontinuous variation
qualitative / clear categories / monogenetic / epistasis may occur / alleles have LARGE effect on phenotype / different loci=different effect
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Define: monogenetic
a phenotype controlled by ONE gene
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Q: characteristics of continuous variation
quantitative / wide/no categories / polygenetic / no epistasis / alleles have SMALL effect on phenotype (additive) / different gene=combined effect on phenotype
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Define: polygenetic
a phenotype controlled by a combination of genes
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Q: what type of variation involves epistasis
discontinuous
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Q: in which variation does an allele have a LARGE effect on the phenotype
A: discontinuous
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Q: in which variation does an allele have a SMALL/ADDITIVE effect on the phenotype
A: continuous
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Q: what type of variation is monogenetic and which is polygenetic
A: monogenetic = discontinuous / polygenetic = continuous
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Q: what do the symbols represent P + Q = 1
A: P=freq of dominant allele / Q=freq of recessive allele
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Q: what do the symbols represent P + Q + 2PQ = 1
A: P = freq of dominant genotype / Q = freq of recessive genotype / 2PQ = freq of heterozygous genotype
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Q: Hardy-Weinberg formulas
A: P + Q = 1 / P + Q + 2PQ = 1
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Define: population
a group of the same species in the same place and the same time who can interbred
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Define: Gene pool
the set of genetic information carried by a population
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Q: 5 conditions for Hardy-Weinberg
A: no mutation / no selection(or selective advantage) / no migration / random mating / large population
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Q: what are environmental factors and what to they produce
A: factors caused by the environment which limit the growth of a population and offer environmental resistane
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A: what happens if there is a big enough environmental resistance (caused by change in the environment)
A: population decrease / competition decreases / population increases / intraspecies competition increases (food/mates/space)
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Define: isolation mechansims
a mechanism in which a large population is split into smaller sub-groups
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Q: types of isolation mechansims
A: reproductive / geographical / seasonal
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Define: stabilising selection
natural selection where allele and genotype frequency remain STABLE because they are already well adapted
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Define: directional selection
natural selection where allele and genotype frequency CHANGE leading to an EVOLUNTIONARY change to become better adapted
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Define: genetic drift
the change in allele frequency of a population where some alleles are passed on and some are eliminated
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Define: genetic erosion
the loss of an allele from a population which reduces genetic variation
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Q: as population size decreases the fluctuation of allele frequency _____
A: INCREASES
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Define: Selection pressure
an environmental factor which improves the survival to reproductive age, where advantageous characteristics can be passed onto their offspring
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Q: what is the chi-squared ( ) test
a test used to find the difference between observed and expected data to determine whether the difference is due to chance
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Q: chi-squared ( ) test can only be used when
A: categorised data / explanation for expected outcomes / no zero values / only numbers / no ratios / large sample size
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Q: what hypothesis do we test in the chi-squared test
A: nulls hypothesis
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Q: what is nulls hypothesis
A: states that there is no significant difference between observed and expected data, and any difference is due to chance
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Q: the smaller the value for chi-square the.....
A: the more likely the difference is due to chance
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Q: the greater the value for chi-square the.....
A: the more likely the difference is due to another factor
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The biological species concept
a group of similar organisms who can interbred to produce fertile offspring
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the phylogenetic species concept
a group of organisms with similar, morphological, behavioural, embryological, ecolcogical and physiological characteristics
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Q: problems with The biological species concept
A: some only reproduce asexually / cannot class extinct or fossils / some members looks very different (males/females)
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Q: problems with The phylogenetic species concept
A: hard to draw the line between species (too many similar genes) / evoluntionary trees are very complex
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Q: name the two concepts for the term species
Q: biological / phylogenetic species concept
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Define: cladistics
the use of DNA and RNA sequencing to determine evolutionary relationships between species
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Q: which species concept uses cladistics
A: phylogenetic species concept
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Define: polyploidy
when there is more than one diploid set of chromosomes in the nucleus
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Q: when is polyploidy likely to occur?
metaphase I / anaphase I if they do not separate properly
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Q: why does polyploidy result in sterile hybrids becoming fertile
A: even number of chromosomes so homologous pairs can form
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Other cards in this set

Card 2

Front

Q: where is DNA found?

Back

A: nucleus of EUKARYOTIC cells

Card 3

Front

Q: nucleic acids consist of

Back

Preview of the front of card 3

Card 4

Front

Q: structure of purines

Back

Preview of the front of card 4

Card 5

Front

Q: structure of pyrmidines

Back

Preview of the front of card 5
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