DNA structure & replication
Recall the structure of DNA
Phosphate, sugar and nitrogenous base
Extra points - hydrogen bonds between base pairs
Define the term genome
A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA.
What is a gene mutation?
A change in the DNA sequence
Recall a modern application of biotechnology.
It can be applied to parcels and packaging, hydrocarbons, chemical products, cosmetics, biofuels, renewable fuels, textiles. It is used in the science, biochemistry, forensics and medical fields to track and
What is the role of helicase in DNA replication?
Unwinds the double helix and separates the strands
Crossing over and independent assortment
What is an intron?
Introns are noncoding sections of an RNA transcript, or the DNA encoding it, that are spliced out before the RNA molecule is translated into a protein.
What is a chromosomal mutation?
Chromosomal mutations involve changes in the number or structure of chromosomes
What is the role of DNA ligase?
If two pieces of DNA have matching ends, DNA ligase can join them together to make an unbroken molecule.
What is the role of DNA polymerase in the process of DNA replication
DNA polymerase synthesises the complementary bases
Recall three differences between spermatogenesis and oogenesis.
Spermatogenesis
- takes place everyday from puberty onwards
- occurs in the testes
- millions of sperm produced each day
- results in 4 haploid sperm cells
Oogenesis
- resting state takes place from embryonic stage to puberty
- ovum is produced once a month
- results in one haploid ovum and two polar bodies
- occurs in the ovaries
Contrast incomplete dominance and codominance
In codominance, both alleles in the genotype are seen in the phenotype. In incomplete dominance, a mixture of the alleles in the genotype is seen in the phenotype
Provide 3 examples of mutagens.
UV radiation, ionising radiation, heat and chemical
Teacher discretion
Describe three differences between prokaryotic DNA and eukaryotic DNA
Prokaryotic
- circular
- no histone proteins
- not found in the nucleus
Eukaryotic
- double stranded helix
- organised in chromosomes within the nucleus
- bound to histones
At what stage of meiosis does crossing over occur?
Prophase 1
What is the HOX gene?
The Hox family of transcription factors is a set of master control genes that regulate the development of the body plan in invertebrates, such as Drosophila, and in vertebrates.
What is the chromosomal mutation called that results in Turner syndrome where there is only one X chromosome?
Monosomy (on chromosome 23)
Explain the purpose of polymerase chain reaction (PCR) and gel electrophoresis
Polymerase chain reaction, or PCR, is a laboratory technique used to make multiple copies of a segment of DNA. PCR is very precise and can be used to amplify, or copy, a specific DNA target from a mixture of DNA molecules.
Gel electrophoresis is a laboratory method used to separate mixtures of DNA, RNA, or proteins according to molecular size. In gel electrophoresis, the molecules to be separated are pushed by an electrical field through a gel that contains small pores.
Recall the theory that associates mitochondria, chloroplasts and prokaryotes.
Endosymbiotic theory
The mitochondria and chloroplast in eukaryotic cells were once bacteria (prokaryote) that were ingested by a large bacteria (prokaryote) and then formed functional organelles of eukaryotes.
How are polar bodies formed during oogenesis?
In oogenesis, the primary oocyte is divided meiotically into the secondary oocyte and polar body, and then the polar body undergoes meiosis II to produce two polar bodies.
Describe the process of protein synthesis
Explain how non-disjunction leads to aneuploidy
Nondisjunction is the failure of chromosomes to separate (disjoin) at anaphase during meiosis I (paired homologs), meiosis II (sister chromatids), or mitosis (sister chromatids), giving rise to daughter cells with an incorrect number of chromosomes.
Describe the process of making recombinant DNA.