Genetics Flashcards
What are chromosomes made of?
Chromosomes are made up of DNA and protein.
What is the length of a chromosome composed of?
The length of a chromosome is made up of many units of DNA called genes.
What is a gene?
A section of DNA that codes for the formation of a protein.
What does ‘locus’ refer to?
Locus refers to the position of a gene on a chromosome.
What are homologous chromosomes?
Homologous chromosomes are chromosomes which carry genes for the same characteristics or traits.
What are alleles?
Alleles are alternative forms of the same gene.
What is a dominant allele?
The allele that gets expressed over the other allele
How is a dominant allele represented?
A dominant allele is represented by an uppercase letter.
What is a recessive allele?
A recessive allele is an allele whose expression is prevented by the dominant allele.
How is a recessive allele represented?
A recessive allele is represented by a lowercase letter.
What is a genotype?
The genotype is the genetic makeup of an organism.
What is a phenotype?
The phenotype is the physical makeup of an organism.
What are homozygous alleles?
Homozygous alleles are a pair of identical alleles for a characteristic or trait.
What are heterozygous alleles?
Heterozygous alleles are a pair of different alleles for a characteristic.
What is incomplete dominance?
Incomplete dominance occurs when the heterozygous genotype gives a different phenotype from either of the homozygous genotypes.
What are gametes?
Gametes are haploid cells capable of fusion.
What is fertilisation?
Fertilisation is the fusion of male and female gametes to form a zygote.
What is progeny?
Progeny are the offspring produced as a result of fertilisation.
What is a pedigree?
A pedigree is a diagram showing the genetic history of a group of related individuals.
Who is known as the father of genetics?
Gregor Mendel is known as the father of genetics.
What did Gregor Mendel study?
Gregor Mendel studied characteristics or traits in the garden pea plant.
What is Mendel’s First Law?
Mendel’s First Law, the Law of Segregation, states that inherited characteristics are controlled by pairs of alleles which separate during gamete formation.
What is a monohybrid cross?
A monohybrid cross is a genetic cross involving the study of one characteristic.
What is Mendel’s Second Law?
Mendel’s Second Law, the Law of Independent Assortment, states that during gamete formation either allele in a pair may enter a gamete with either allele in another pair.
What is a dihybrid cross?
A dihybrid cross is a genetic cross involving the study of two characteristics.
What are linked genes?
Linked genes are genes located on the same chromosome, which do not show independent assortment.
How is sex determined in offspring?
The sex of the offspring is determined by the sex chromosome of the sex cell.
What are autosomes?
Autosomes are chromosomes that do not determine sex. There are 44 autosomes, or 22 pairs.
What are female sex chromosomes?
Female sex chromosomes are XX.
What are male sex chromosomes?
Male sex chromosomes are XY.
What is sex linkage?
A gene (or genes) present on the X (or Y, or sex) chromosome
What are examples of sex-linked conditions?
Examples of sex-linked conditions include colourblindness and haemophilia.
Who is more likely to suffer from sex-linked conditions?
Males are more likely to suffer from sex-linked conditions because they have only one X chromosome.
What is the sugar in DNA
Deoxyribose
What are the structural differences between DNA and RNA
DNA is double stranded, RNA single stranded.
DNA has thymine, RNA has uracil.
DNA is longer than RNA
Where does transcription take place in animal and plant cells
Nucleus
Where does translation occur
Ribosomes
What are three RNA molecule involved in protein synthesis
Messenger RNA, ribosomal RNA, transfer RNA
Describe the events of translation
mRNA goes to a ribosome, tRNA molecules bring amino acids to the ribosome, tRNA binds to mRNA with matching codon or anticodon. sequence of amino acids assembles/ peptide bond formed, the chain folds
What is genetic engineering
Manipulation/ alteration of genes
What are the steps in genetic engineering
Isolation, cutting, transformation and expression
What is isolation in genetic engineering
Identifying or locating gene
What is expression in genetic engineering
The gene that causes the production of protein or product
Name the rings of DNA contained in bacteria that may be used as cloning vectors
Plasmids
What’s an application of genetic engineering in animals, plants and microorganisms.
Animals: lactose free milk.
Plants: slow ripening.
Microorganisms: production of antibiotics.
In genetics, what is meant by segregation?
Separation of homologous chromosomes
or separation of alleles
Make three points on complementary base pairs
bases joined by) hydrogen bonds / purine with pyrimidine /
Cytosine with Guanine / Adenine with Thymine in DNA /
Explain how meiosis contributes to variation.
It rearranges genetic material or it produces non-identical cells
Describe three points put forward in the theory of natural selection,
those with the more adaptive characteristics survive (or survival of the fittest) / the others are eliminated (or die out) / the survivors reproduce (or breed) /
Give one piece of evidence that supports the theory of natural selection.
Fossils
Describe transcription
- DNA double helix is unwound by enzyme helicase at the start of the gene
and stops at the end of the gene. - RNA free nucleotides enter and bond with 1 strand of exposed DNA
bases. - RNA polymerase joins these nucleotides to produce a
strand of RNA called mRNA. The mRNA bases are complementary to the DNA bases on one strand. - Once it reaches the end of the gene the mRNA falls off the DNA
sequence and the DNA winds back up to a double helix shape. - mRNA leaves nucleus and enters cytoplasm.
What are the differences between DNA replication and transcription
DNA: unwinds all way along, free DNA nucleotides and DNA polymerase used, both strands copied and 2 double helix’s produced.
Transcription: only unwinds at gene site, RNA nucleotides and polymerase used, one strand copied and 1 mRNA strand produced
