B12b Inheritance Flashcards
What are gametes?
Sex cells
Haploid (half number of chromosomes)
What is a chromosome?
A long coiled molecule of DNA that carries genetic information
Define the term gene?
A small section of DNA on a chromosome
Codes for a particular sequence of amino acids to make a specific protein
What is an allele?
Different versions of the same gene
What is a dominant allele?
A version of a gene where only one copy is needed for it to be expressed.
What is a recessive allele?
A version of a gene where two copies are needed for it to be expressed
What is meant when an organism is homozygous?
When an organism has two copies of the same allele
(2 recessive or 2 dominant alleles)
What is meant when an organism is heterozygous?
When an organism has two different versions of the same gene.
What is the genotype?
The alleles present at a particular gene
Determine the phenotype of an organism
What is a phenotype?
The visible characteristic
Name the gametes found in plants
Pollen
Egg
Name the gametes in animals
Sperm
Egg
Name the type of cell division used to make gametes
Meiosis
How many chromosomes are found in human body cells?
46
How many chromosomes are found in human gametes?
23
How are dominant and recessive alleles shown in a genetic diagram?
Dominant - capital letter
Recessive - lower case letter
The same letter is used for the gene
Give an example of a characteristic which is controlled by a single gene
Fur colour in mice
Red green colour blindness in humans
Most characteristics are the result of multiple genes rather than a single gene. True or false?
True
What is meant by an inherited disorder?
Caused by the inheritance of certain alleles
Give an example of a genetic condition caused by a dominant allele
Polydactyly
Describe the phenotype shown by a person with polydactyly
Extra fingers or toes
Give an example of a genetic condition caused by a recessive allele
Cystic fibrosis
Give the genotype for a person with cystic fibrosis
ff
Give the possible genotypes of a person with polydachtyly
DD
Dd
Give the genotype of a human female
XX
Give the genotype of a human male
XY
What are the sex chromosomes?
A pair of chromosomes that determine the biological sex
What is sexual reproduction?
Type of reproduction
There is mixing of genetic information from two parents
Involves gametes made by meiosis
The offspring show variation
What is asexual reproduction?
Type of reproduction
Only one parent involved
No mixing of genetic information
Only mitosis is involved
All the offspring a re genetically identical (clones)
What happens to the number of chromosomes in the cells produced by meiosis?
Halved
Describe the events that take place in meiosis
The genetic material is copied (DNA replicated)
Cell divides twice to form 4 gametes
Each gamete has a single set of chromosomes
All gametes are genetically different
Name the organs where meiosis takes place
Male - testis
Female - ovary
The B allele produces brown eyes
The b allele produces green eyes
Give the genotypes of a person with brown eyes
BB
or Bb
The B allele produces brown eyes
The b allele produces green eyes
What percentage of the offspring will have brown eyes
75%
The B allele produces brown eyes
The b allele produces green eyes
What is the genotype of a person with green eyes?
bb
What proportion of the offspring will have purple flowers
75%
What colour flower is produced by the homozygous recessive
White flower
What is the genotype of a female child?
XX
What is the ratio of male and female offspring on this punnet square
1:1
Describe the shape of a DNA molecule
Double helix
What does the term genome mean?
The entire genetic material of that organism
Where is the genetic material found in a cell?
Nucleus
Chromosomes
Name the chemical found in the genetic material
DNA
Describe the structure of DNA
A polymer
Made of two strands
Forms a double helix
Why is the understanding the human genome important?
Search for genes linked to different disease
Understand an treat inherited disorders
Trace human migration patterns in the past
What are the advantages of using the human genome?
Search for genes that cause disease
Treatment of genetic disorders
Tracing human migration patterns from the past
Describe the shape of this molecule
Double helix
Name this molecule
DNA
