Genetics & DNA

Exam flashcards 1

Three parts of a nucleotide

Deoxyribose sugar, Nitrogenous base, Phosphate group

What is the overall shape of DNA?

Double helix

What holds the structure of DNA together?

Phosphodiester bonds, Hydrogen bonds, Base stacking

Complementary base pairing rules?

A and T, G and C

What does A, C, G, & T stand for?

Adenine, Cytosine, Guanine, Thymine.

Where is DNA primarily located?

In the nucleus.

What are the levels of organisation?

Cells, Nucleus, Chromosome, DNA, Gene

Definition of gene?

A gene is the basic physical and functional unit of heredity.

Definition of allele?

An alternative form or variant of a gene.

What is a genotype?

The complete genetic makeup of an organism, or more specifically, the specific set of genes or alleles inherited for a particular trait.

What is a phenotype?

The set of observable characteristics or physical traits of an organism.

What is the difference between a genotype and phenotype?

A genotype is an organism’s complete set of genetic material or underlying DNA sequence. A phenotype is the observable physical expression or measurable characteristics of those genes (e.g. hair colour, height, or blood type.)

What is a mutation?

A permanent change in the DNA sequence of an organism.

What are the causes of variation in population?

Fertilisation, Meiosis, Mutation

How does variation arise in a population?

From three core mechanisms:

Mutations

Gene recombination during sexual reproduction

Gene flow

Identify genotypes of offspring

An offspring’s genotype is the specific combination of alleles inherited from its parents. Offspring recieves one allele from each parent, which dictates their physical traits (phenotype)

Predict phenotypes using dominance

The dominant allele takes over the recessive allele in a heterozygote. (B-brown is dominant, b-blue is recessive. BB and Bb result in brown eyes, only bb results in blue.)

How does DNA act as a manual for traits?

By using a four-letter chemical alphabet (A, C, T, G) to create genes. The proteins are building blocks that determine your physical traits.

What does DNA stand for?

Deoxyribonucleic Acid