Human Biology UNIT 4 Learning Objectives

Semester Two Human Biology Exam Revision

Mutagen

Any factor that increases the rate at which mutations occur.

Explain how a mutation can be passed onto offspring.

Mutations occur in gametes and the affected gamete undergoes fertilisation to produce mutated offspring.

Define gene mutation and state some conditions caused by this type of mutation.

An alteration to a singular gene. This can cause:

• Cystic fibrosis

• Duchenne’s muscular dystrophy

• Albinism

Define chromosomal mutation and state some conditions caused by this type of mutation.

A change to the structure or number of chromosomes in an organism, causing an alteration to many genes. This can cause:

• Down syndrome

• Patau syndrome

• Klinefelter syndrome

• Cri-du-chat syndrome

Define hypothyroidism and list some symptoms.

A condition characterised by the under activity of the thyroid gland, causing low levels of thyroxine in the blood.

• slow heart rate

• fatigue/lack of energy

• intolerance to cold

• goitre

• weight gain

Outline the process of recombinant DNA technology that would produce a synthetic hormone to treat hypothyroidism.

The gene for thyroxine is isolated cut out using restriction enzymes. Then a bacterial plasmid is removed and cut using same restriction enzyme. The human gene is then spliced and added into plasmid using DNA ligase. The bacterium is treated to take up recombinant plasmid and the plasmid gets introduced back into the bacterium. The bacterium will multiply and be stimulated to produce thyroxine.

Identify the species that is most closely related to Homo sapiens.

Homo neanderthalensis

Identify the species that is most distantly related to Homo sapiens.

Australopithecus afarensis

Identify the features of the jaw and teeth that classify an Australopithecine.

• U-shaped and slightly parabolic shape of dental arcade

• Prognathic jaw

• Absence of chin

State reasons why fossil records remain incomplete.

• conditions for fossilisation are rare

• many fossils are inaccessible or not yet discovered

• fossils have been damaged by human activity/animals/movements of Earth’s crust

Distinguish between a ‘relative date’ and an ‘absolute date’.

Relative date is the age of a fossil in comparison to another fossil whereas the absolute date is the actual age of a fossil in years.

Define “biotechnology”

The use of cellular processes to make products that are of use to humans

Describe the structure of DNA, including the nucleotide unit.

DNA is a polymer

•Explain the function of DNA, in terms of genes, the genetic code and protein production.

•Explain how DNA is able to control the activity of a cell, in terms of the manufacture of proteins eg enzymes

•Outline what recombinant DNA technology is.

•Define “transgenic organism”.

•Explain what restriction enzymes are and why they are important for the purpose of creating recombinant DNA.

•Describe what a recognition site is, sticky ends and blunt ends.

•Give the function of the enzyme DNA ligase.

•Outline how a bacterial plasmid can be used as a vector to create recombinant DNA.

•Outline how a virus can be used as a vector to create recombinant DNA (not in text)

•Describe how recombinant DNA techniques are used to produce insulin, hGH, Factor VIII and vaccines.

•Describe how various biotechnological techniques are integrated to permit the identification of hereditary diseases.

•Using cystic fibrosis as the example, explain what gene therapy is and extend this to explain how gene therapy could be used as a treatment for diabetes mellitus.

•Describe hyperthyroidism, including the most common symptoms.

•Give some known causes of hyperthyroidism.

•Describe the most common form of hyperthyroidism, Graves’ disease

•List the treatments for hyperthyroidism.

•Describe hypothyroidism, including the most common symptoms.

•Give some known causes of hypothyroidism.

•Describe the most common observable symptom of hypothyroidism, a goitre.

•List the treatments for hypothyroidism.

•Give one risk associated with using hormones to treat hypothyroidism.

•Explain how and why diabetes sufferers can become hyperglycaemic.

•Distinguish between type 1 and type 2 diabetes.

•Explain why diabetes represents a good example of a disruption to homeostasis.

•Describe the treatments for insulin-dependent diabetes.

•List the risk factors for type 2 diabetes.

•Explain why insulin treatment generally does not work for adult-onset diabetes.

•Describe the treatments for adult-onset diabetes.

•Define “species”, “population” and “gene pool”.

•List and describe the processes that can contribute to increased variation within a population.

•Recall the general function of DNA, in terms of genes, the genetic code and protein production

•Recall how DNA is able to control the activity of a cell, in terms of the manufacture of proteins/enzymes

•Explain what is meant by genotype and phenotype

•State that different cells produce different proteins depending on which genes are activated

•State that gene expression means the mechanism whereby a gene has its effect within a cell (which means in other words that it is when the gene is “switched on” and the protein is being manufactured) NB No details of gene expression or epigenetics required.

•Distinguish between genes and alleles.

•Using an example, explain what allele frequency means.

•Outline how rates of survival are determined by the interaction between phenotypes in a population and the environment

•Define “mutation”.

•Outline the role of DNA replication in cell division and how gene mutations can arise when errors are made during this process

•Outline how chromosomal mutations can arise during the meiotic processes of crossing over and non-disjunction

•Define and give examples of mutagens.

•Distinguish between gene mutations and chromosomal mutations.

•Distinguish between somatic and germline mutations.

•Describe, with examples, the effects of gene mutations.

•Describe, with examples, the effects of chromosomal mutations.

•List and describe the types of chromosomal mutations.

•Identify chromosomal abnormalities from a karyotype.

•Outline what a lethal recessive is.

•Describe, using examples, the impact that mutations have on variation and the significance of this variation to the survival of a population.

•Define evolution two ways; in terms of observable changes to phenotype and in terms of the gene pool

•Outline why variation is important for the survival of a population in an environment that is changing

•State the reason why mutations can lead to changes to allele frequencies in a gene pool.

•Outline what is meant by a “survival advantage”

•Define “selection pressure”

•Define natural selection.

•List the key elements of evolution by natural selection.

•Describe how differences in body stature represent an example of natural selection in humans.

•Outline how migration can cause changes to allele frequencies in a population.

•Quote examples of where migration has influenced allele frequencies.

•Define “gene flow”.

•Outline how barriers to gene flow can cause changes to allele frequencies in a population.

•Give examples of geographical barriers and sociocultural barriers.

•Define genetic drift.

•Using an example (such as the Dunkers) describe genetic drift.

•Describe the founder effect.

•Using a specific example, explain how the founder effect can cause changes to allele frequencies in a population.

•Justify why the founder effect represents genetic drift.

•Identify when the Founder Effect is occurring.

•Outline the causes and symptoms of sickle-cell anaemia.

•Describe the inheritance of sickle-cell anaemia.

•Using the inheritance of sickle-cell trait, explain how alleles that cause fatal genetic diseases can persist in human populations.

•Using sickle-cell anaemia, explain how factors in the environment can confer (give) a selective advantage on certain phenotypes.

•Compare genetic drift with natural selection in terms of [i] cause [ii] influence of selection pressures [iii] change in gene frequencies [iv] likelihood of occurring [v] adaptive value (not in text).

•Define speciation.

•Describe how speciation occurs, in terms of variation, struggle for existence, isolation and differential selection, producing changes to gene pools.

•Outline some of the issues around the species definition, including hybridisation.

•Define “genome”.

•Explain why it would be expected that as one species gives rise to another, their respective genomes would become different.

•Outline how a percentage difference would be determined for two different species, when a genomic DNA study is carried out (not explicit in text).

•Explain, in general terms, how non-coding DNA sequences provide evidence for species sharing a common ancestor.

•Outline how PCR and electrophoresis might be used as part of a DNA study.

•Describe the PCR process occurring in a thermal cycler.

•Distinguish between the three stages of PCR; denaturing, annealing & elongation

•Explain why each PCR stage requires a specific temperature

•Give the temperature at which each PCR stage occurs

•Describe what a primer is, and what it can be used for.