GLENDOWIE COLLEGE – YEAR 13 BIOLOGY
ACHIEVEMENT STANDARD: BIOLOGY 3.3
DESCRIBE GENE EXPRESSION
Credits: 4
Assessment: External
UNIT 1: ROLE OF DNA IN GENE EXPRESSION
SPECIFC LEARNING OUTCOMES:
By the end of this unit, students should be able to:
 Explain what a cell is
 Explain the difference between a prokaryote and eukaryote
 State examples of a prokaryote and eukaryote
 Explain the difference between animal and plant cells
 Explain what chromosomes are
 State where chromosomes are found in a cell
 Explain the difference between chromosomes in prokaryotes and
eukaryote
 Explain what genes are
 Describe the relationship between genes are chromosomes
 Explain what a homologous pair is
 Explain what a centromere is
 Explain how a homologous pair of chromosomes can be identified
 Explain what a zygote is
 Explain what gametes are
 Explain what fertilisation is
 Describe the difference between a somatic and sex cell
 Name the gametes in animals and plants
 Describe the difference between asexual and sexual reproduction
 Describe the difference the haploid and diploid number
 State the haploid and diploid number in humans
 Describe what cell division is
 Explain the difference between a parent and daughter cell
 Explain the purpose of mitosis
 State where mitosis occurs
 Describe the genetic makeup of the daughter cells in comparison
to the parent cell
 State how many daughter cells are produced from each parent cell
 Describe the 4 stages of the cell cycle
 Describe the process of mitosis (IPMAT)
 Explain the difference between nuclear division and division of the
cytoplasm (cytokinesis)
 Define the words: chromatin and chromatid
 Explain the purpose of meiosis
 State where meiosis occurs
 Describe the genetic makeup of the daughter cells in comparison
to the parent cell
 State how many daughter cells are produced from each parent cell
 Describe the process of meiosis
 Explain how meiosis reduces the chromosome number (from
diploid to haploid)
 Explain how meiosis produces genetic variation through
independent segregation
 Explain how meiosis produces genetic variation through crossing
over
 Define the words: bivalent, tetrad, chiasma, sister chromosomes,
non-sister chromosomes
 Describe the relationship between fertilisation, mitosis and meiosis
 Describe what a karyotype is
 Explain how a karyotype is different for a male and female
 Explain how a karyotype shows abnormalities
 Explain the difference between an autosome and a sex
chromosome
 Explain what a genome is
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Explain the difference between DNA and a chromosome
Explain what DNA is made up of
State the groups that make up a nucleotide
State the 4 bases and the symbols used to represent them
Describe the difference between a pyrimidine and purine
Describe the difference between a nucleotide and a nucleoside
Describe the shape of a DNA molecule
Explain why the ends of the DNA are labelled 3’ and 5’
Explain why the two chains in a DNA molecule are called
antiparallel
Explain how bases pair in a DNA molecule
State the weak bonds that are formed between bases
Describe the function of DNA
Describe the differences between DNA and RNA
Explain what a nucleic acid is
Give two examples of a nucleic acid
Explain when DNA replication occurs
Explain why DNA replication is called semi-conservative
Describe the process of DNA replication
Describe the role of the following enzymes in DNA replication:
Helicase, RNA polymerase, DNA polymerase, DNA ligase
Describe the difference between the leading and lagging strand
Explain what Okazaki fragments are and why they occur
Explain what is meant by a complementary strand
Explain what a protein is
State the uses of proteins in the body
Explain what a polymer is
Describe what proteins are made up of
Define the word enzyme
Explain the relationship between an enzyme and a protein
Explain how enzymes speed up reactions
Describe the difference between anabolic and catabolic reactions
Explain what is meant by enzymes being specific
Describe the process by which enzymes are thought to work
Explain what an active site is
Explain how co-factors or co-enzymes work
Describe what an amino acid is
Explain what a polypeptide chain is
Describe the relationship between genes, amino acids and
proteins
State how many different amino acids there are
Describe the structure of an amino acid
Explain how condensation reactions make polypeptide chains
longer
Explain how hydrolysis reactions make polypeptide chains shorter
Explain the difference between a peptide bond, a dipeptide, a
tripeptide and a polypeptide
Explain what primary structure is
Explain how primary structure makes each protein unique
Explain what secondary structure is
Describe the difference between an alpha (α) helix and a beta (β)
sheet
Explain what tertiary structure is
Explain what quaternary structure is
Explain what not all proteins have quaternary structure
Describe the structure of the 3 types of RNA
Describe the roles of the 3 types of RNA
Explain what protein synthesis is
State the 3 stages of protein synthesis
Describe the process of transcription
Explain the difference between the coding (sense) strand and the
template (antisense) strand
State the direction in which the RNA strand grows
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Describe the process of RNA processing
Describe the difference between introns and exons
Describe the process of translation
Explain the difference between a triplet, a codon and an anticodon
Explain the relationship between one gene and one polypeptide
Explain what is meant by the genetic code
Explain why the genetic code is described as universal
Explain why the genetic code is called degenerate
Explain why a 3-lettered codon is used to code for amino acids
Use an mRNA table to work out an amino acid when given a 3
base sequence
State the START and STOP codons
Explain the significance of the START and STOP codons
UNIT 2: Control of Gene Expression
SPECIFC LEARNING OUTCOMES:
By the end of this unit, students should be able to:
 Describe the role of enzymes in living things
 Explain how enzymes allow reactions to occur more rapidly
 Explain what an active site is
 Explain what the lock and key model is
 Draw a diagram to show how the lock and key model works
 Explain what the induced fit model is
 Draw a diagram to show how the induced fit model works
 Explain what a metabolic pathway is
 Explain how enzymes control metabolic pathways
 Explain the difference between anabolism and catabolism
 Explain how end-product inhibition controls the amount or activity
of an enzyme that is regulating a metabolic pathway
 Using an example explain how an enzyme malfunction is
responsible for the occurrence of a specific metabolic disorder e.g.
PKU
 Explain what the operon model is
 Explain what an operon is
 Describe the role of a structural gene, promoter, operator,
regulator gene and repressor molecule
 Explain how structural genes are switched on
 Explain how metabolic pathways are regulated in prokaryotes
through gene induction
 Explain what a repressor is
 Explain how the end-product of a metabolic pathway can activate
a repressor and switch genes off (gene repression)
 Explain the difference between an inducible and non-inducible
system
 Describe the regulation of gene expression in eukaryotes
 Describe the roles of the promoter region, RNA polymerase,
transcription factors, enhancers and the terminator sequence
 Explain what carcinogens are
 Explain what cancer is
 Describe the factors that increase the chances of cancerous
growths
 Explain how carcinogens can upset the normal controls of
regulating cell division
 Describe the roles of tumour suppressor genes and oncogenes
UNIT 3: Mutations
SPECIFC LEARNING OUTCOMES:
By the end of this unit, students should be able:
1. To understand what a mutation is
 Explain what a mutation is
 Explain what a mutant is
 State the two main types of mutations
 Explain the difference between gene and chromosomal mutations
2. To learn how mutagenic agents cause mutations
 Explain what a mutagenic agent or mutagen is
 Describe the difference between spontaneous and induced
mutations
 State some examples of mutagenic agents
 Explain how these mutagenic agents cause mutations
3. To learn about the effects of mutations
 Explain why somatic mutations have less significant impact on a
species than those that occur in gametes
 Explain why most mutations are not expressed
 Explain what is meant by a neutral (silent) mutation
 Give an example of how a mutation can be beneficial
 Give an example of how a mutation can be harmful
4. To understand gene mutations
 Explain what is meant by a gene mutation
 Explain the difference between mutations involving a change in a
single nucleotide (point mutation) and those involving changes to a
triplet
 Explain why gene mutations offer the greatest evolutionary potential
 Describe an example of a point mutation e.g. sickle cell mutation
 Describe an example of a triplet deletion eg. Cystic fibrosis
 Describe the cause of each of the following: base substitution, base
deletion, base insertion
 Describe the effects of each of the following: base substitution,
base deletion, base insertion
 Explain what is meant by a frame shift
5. To understand chromosome mutations
 Explain what a chromosome mutation is
 Describe each of the following mutations: translocation, inversion,
duplication, deletion
 Describe the genetic effects of the following mutations:
translocation, inversion, duplication, deletion
 Explain the difference between a chromosome block mutation and
a chromosome number mutation
6. To understand aneuploidy
 Explain what aneuploidy is
 Define the word non-disjunction
 Describe how non-disjunction causes aneuploidy
 Explain the terms: nullisomy, monosomy, disomy, trisomy and
polysomy
 Give example of nullisomy, monosomy, disomy, trisomy and
polysomy
 Explain what a syndrome is
 Explain the significance of Barr bodies to the expression of
aneuploid syndromes
 Describe examples of aneuploidy in human sex chromosomes e.g.
Turner’s syndrome
 Describe an example of polysomy in human autosomes e.g.
Down’s syndrome – Trisomy 21
 Explain what is meant by the maternal age effect
7. To understand polyploidy
 Explain what polyploidy is
 Describe how polyploidy occurs
 Describe the difference between allopolyploidy and autopolyploidy
 Describe how polyploidy has been important in the development of
a modern crop variety e.g. wheat
 Explain how polyploidy can generate new fertile species from a
sterile hybrid of two existing species
UNIT 4: Gene Interactions
SPECIFIC LEARNING OUTCOMES:
(1)To understand Mendel’s contribution to genetics
 Explain who Mendel is and briefly outline his experiments
 Explain what a locus is
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Describe the difference between a character and a trait
Describe the relationship between a gene and an allele
Describe the difference between genotype and phenotype
Describe the difference between homozygous and heterozygous
Explain what dominant and recessive alleles are
Explain what is meant by true or pure breeding
Explain what the first filial (F1) and second filial (F2) generation are
(2) To learn how to use a Punnet square to carry out a monohybrid cross
 Explain what a monohybrid cross is
 Carry out a monohybrid cross
 State the phenotypic ratio expected when carrying out a
monohybrid cross between two heterozygotes
(3) To learn how carry out a monohybrid test cross
 Explain what the testcross is used for
 State the phenotypic ratio expected for a heterozygote and
homozygote
 Explain Mendel’s First Law (The Law of Segregation)
(4) To understand the exceptions to the 3:1 ratio expected from a
monohybrid
 Explain what incomplete dominance is
 State the phenotypic ratios expected in an incomplete dominance
cross
 Explain what co-dominance is
 State the phenotypic ratios expected in a co-dominance cross
 Explain what over dominance is
 State the phenotypic ratios expected in an over dominance cross
 Explain what lethal genes are
 State the phenotypic ratios expected from a cross involving lethal
genes
(5) To understand what multiple alleles are
 Explain what multiple alleles are
 Describe an example where multiple alleles exist for a single gene
(e.g. ABO blood groups
 Solve problems involving the inheritance of phenotypic traits
involving multiple alleles
(6) To learn how to use a dihybrid cross to analyse inheritance
 Explain the difference between a monohybrid and dihybrid cross
 Describe the relationship between a monohybrid and dihybrid cross
 Use a dihybrid cross to solve problems involving inheritance
 State the phenotypic relationship expected when carrying out a
dihybrid cross between two heterozygotes
(7) To learn how carry out a dihybrid test cross
 Explain what the dihybrid testcross is used for
 State the phenotypic ratio expected for a heterozygote
 Explain Mendel’s Second Law (The Law of Independent Assortment)
(8) To understand the exceptions to the 9:3:3:1 ratio expected from a
dihybrid cross
 Explain what epistasis is
 Explain what complementary genes are
 State the phenotypic ratios expected in a dihybrid cross involving
complementary genes
 Explain what duplicate genes are
 State the phenotypic ratios expected in a dihybrid cross involving
duplicate genes
 Explain what supplementary genes are
 State the phenotypic ratios expected in a dihybrid cross involving
supplementary genes
 Explain what collaboration is
 State the phenotypic ratios expected in a dihybrid cross involving
collaborative genes
(9) To understand polygenic inheritance
 Explain what polygenic inheritance is
 Describe the distribution pattern of phenotypic variation produced by
polygenic inheritance
 Explain why polygenes are also called multiple genes
 Describe ane example of polygenic inheritance e.g. skin colour
 Describe the difference between continuous and discontinuous
variation
 Explain the genetic basis for continuous and discontinuous variation
(10) To understand pleiotropy
 Explain what pleiotropy is
 Describe the difference between pleiotropy and epistasis
 Describe an example of pleiotropy e.g. sickle cell gene mutation
(11) To understand how sex is determined
 Describe the basis of sex determination in humans and other
mammals
 Explain the difference between the heterogametic and homogametic
sex
(12) To understand what sex linkage is
 Explain what is meant by sex linkage
 Explain why sex chromosomes are only partly homologous
 Describe examples of sex linked inheritance (e.g. red-green colour
blindness, haemophilia)
 Solve problems involving sex linked inheritance
 Explain how Punnet squares involving sex linked genes differ from
normal monohybrid crosses
 Describe the difference in the pattern of inheritance for sex linked
recessive traits and sex linked dominant traits
(13) To learn how to use Pedigree charts to analyse inheritance
 Explain what a pedigree is
 Describe the symbols used in pedigree analysis charts
 Use the charts to determine the probability of certain offspring
having particular traits
 Describe the difference in the pattern of inheritance for autosomal
dominant and recessive traits and sex linked recessive and
dominant traits
(14) To understand linkage
 Describe the difference between linkage and sex-linked genes
 Describe the effect of linkage on the inheritance of alleles
 Describe the effect of linkage with cross over on the inheritance of
alleles
 Explain what recombination is
 Explain what recombinants and non-recombinants are
(15) To learn how to make a chromosome map
 Explain what the cross over value is (COV)
 State the equation used to work out the COV
 Use the equation to work out crossover values
 Explain what crossover values are used for
 Use crossover values to construct a chromosome map
(16) To understand how the environment modifies phenotype
 Explain how both genotype and environment contribute to
phenotypic variation
 Describe the difference between direct and indirect environmental
influences
 Give examples of both direct and indirect environmental influence on
phenotype