4.6.1.3 DNA and the genome Flashcards
What does DNA stand for?
Deoxyribonucleic acid
What is the role of DNA
contains the instructions needed for an organism to develop, survive and reproduce
What are chromosomes
These are coiled threads of DNA found in the nucleus of all cells
What is a gene?
A length of DNA that codes for the making of particular protein (unit of inheritance)
What is a genome?
Complete set of genes and its instructions
What are bases?
4 types and their sequence determines the genetic instruction
What are alleles?
Different varieties of a gene which code for a different version of the same characteristic (e.g eye colour)
What is a diploid?
Containing two sets of chromosomes
The difference between one molecule of DNA ( or gene) and another depends on the…
Order of the base pairs
Why is there an unlimited number of possible arrangements of genes in an organism?
Because each organism is different and they vary in base arrangements
Everyone has an unique DNA structure except..
Twins and clones
What is a DNA molecule known as?
A double helix
What are the 2 pairing base pairs in DNA?
Adenine - thymine
Guanine - cytosine
State two properties of a double helix
DNA is coiled to form the arms of the chromosome
Cross sections made up of base pairs
State information about the genome
This is all of the information that is in the chromosomes
There are over 20000 genes in humans
A special type of DNA is inherited via mother, comes from egg’s mitochondria.
State properties of the phrase, inheritance.
Characteristics from both dad and mum
Siblings inherit some similar and some different characteristics from parents so may or may not look similar.
What will there be for each characteristic e.g hair colour in the cells?
A certain combination of alleles
What is a genotype?
This is the genes directly found inside of our cells.
What is a phenotype?
The characteristics visible on our appearances
Génotypes may have different alleles, but the ________ one will be expressed in the phenotype.
Dominant
What is a dominant allele
This is a allele more likely to occur
What is a recessive allele
This is an allele less likely to occur
Define the term ‘heterozygous’
This is where there is one dominant allele and one recessive allele
Aa or Bb or cC
Define the term ‘ homozygous ‘
Both dominant alleles or both recessive alleles
AA / aa BB / bb
Are dominant alleles shown as capital letters or lowercase letters?
Capital
Are recessive alleles shown as capital or lowercase letters?
Lowercase
