B6 Inheritance, Variation And Evolution Flashcards
What is DNA?
DNA is a polymer composed of polynucleotides called chains.
What is the structure of DNA?
DNA is a double-helix structure.
What does DNA make up?
Genes
Where are genes found?
On chromosomes
What is a polymer?
A molecule made from many repeating subunits called nucleotides.
What are the 4 bases in DNA structure? (Hint: GATTACA)
- Thymine
- Guanine
- Adenine
- Cytosine
What are the colours for each DNA base? (Hint: GATTACA)
Thymine is yellow.
Guanine is blue.
Adenine is red.
Cytosine is green.
How do the 4 DNA bases pair? (Hint: GATTACA)
Thymine <—> Adenine
Guanine <—> Cytosine
What is a gamete?
A sex cell.
What are gametes in humans?
Sperm and egg cells.
What are chromosomes?
Long threads of DNA made up of genes.
Where are chromosomes found?
The nucleus of a cell.
What is a gene?
A small section of DNA on a chromosome, that codes for a specific sequence of amino acids, to make a specific protein.
What is the unit of heredity?
Genes. They can be copied and passed on for generations.
What are alleles?
Different versions of the same gene (ie. blue/brown eye colour alleles).
What is it called if a person has the same 2 alleles for any gene?
Homozygous
What is it called if a person has 2 different alleles for the same gene?
Heterozygous
What is a genotype?
The collection of alleles that determine characteristics. Can be expressed as a phenotype.
What is a dominant allele?
The dominant allele is always expressed, even if only one is present. In a Punnett square, the dominant allele is represented by a capital letter. For example, if one allele has a dominant gene such as brown eyes, that allele will give you brown eyes.
What is a recessive allele?
The recessive allele is only expressed if the individual has 2 copies. In a Punnett square, it is represented by a lowercase letter.
What does homozygous mean?
The alleles are both identical for the same characteristic.
What does heterozygous mean?
The alleles are both different for the same characteristic.
What are the odds of having a male/female baby?
Always 50%.
What is the male sex allele?
XY
What is the female sex allele?
XX
What are squares which show mono hybrid single gene allele combinations?
Punnett Squares
What is sickle cell anoemia, and is it recessive or dominant?
An inherited disease which alters shape of red blood cells. Caused by a recessive gene.
What is Huntington’s Disease and is it caused by a recessive or dominant gene?
An inherited disease affecting the nervous system of middle aged people. Caused by a dominant gene.
What is polydactyl and is it caused by a recessive or dominant gene?
An inherited disease resulting in extra fingers or toes. Caused by a dominant gene.
What is cystic fibrosis and is it caused by a recessive or dominant gene?
An inherited disease of the cell membranes affecting the lungs and digestive system. Caused by a recessive gene.
What is genetic screening?
Testing people or groups of people for the presence of a particular allele or other genetic abnormality.
What is amniocentesis?
Genetic screening involving using a needle to take some amniotic fluid surrounding a foetus to be analysed.
What is genetic testing?
Analysis of DNA to identify genetic disorders.
What is antenatal testing?
Looking at chromosomes before birth to identify possible disorders.
What is neonatal testing?
Taking a blood sample from a newborn baby to identify possible disorders.
What is pre-implantation genetic diagnosis?
Analysing a grown embryo to identify possible genetic disorders.
