Genetic Crosses and Heredity Flashcards
Ch 16
All body cells except reproductive cells are?
somatic cells
Somatic cells include? (name 3).
cheek, blood, muscle
Definition of gametes?
are haploid cells that are capable of fusion
Definition of fertilisation?
is the fusion of a male gamete with a female gamete
Definition of allele?
form of a gene
What is the locus of a gene?
is it’s position on a chromosome
What does dominant mean in terms of alleles?
the allele that prevents the recessive allele from being expressed
What does recessive mean in terms of alleles?
the allele is masked by the dominant allele
Definition of heredity?
the passing on of traits/features from parent to offspring by means of genes
What is a gene?
a section of DNA that codes for a particular protein
Where are genes located?
on chromosomes
Chromosomes are made up of what two things?
DNA and protein
How many genes do we get from each parent?
One
Name two types of genes.
Dominant and recessive
Definition of genotype?
the genetic make-up of an organism (the genes that are present)
Definition of phenotype?
the physical make-up, or appearance, of an organism
What does progeny mean?
refers to offspring that are produced
Difference between homozygous and heterozygous?
- homozygous: alleles are identical for a trait
- heterozygous: the alleles are different
What does a punnet square show?
the ratio of genotypes of progeny in a genetic cross
What does incomplete dominance mean?
neither allele is dominant or recessive with respect to each other
Definition of a pedigree?
(a diagram showing ) the genetic history of a group of related individuals
Non-sex chromosomes are called?
autosomes
Nucleus of each human somatic cell has how many chromosomes? How are they split?
46 total,
44 non-sex chromosomes = autosomes,
2 sex chromosomes
Give an example of a gender-neutral feature.
skin colour
Two sex chromosomes are called?
X and Y
Is X or Y chromosome longer?
X
XX = what gender?
XY = what gender?
female
male
Do male or female determine gender of child?
male
Name some species where the pattern of determination is the reverse.
butterflies, moths, birds
George Mendel is known as the?
‘father of genetics’
‘Father of genetics’ is who?
George Mendel
What did George Mendel examine?
pea plants on seven characteristics
Where is Mendel from?
Austria
Describe what exactly Mendel did/found out.
he got purple and white pea plants
the purple flowers self-pollinated and so did the white flowers
he made sure he had true breeding plants by looking at many generations produced (purple only produced purple, white only produced white)
Mendel’s first law is called?
the law of segregation
The law of segregation refers to which law?
first
Describe Mendel’s first law/law of segregation.
each trait is controlled by a pair of factors
these factors separate during the formation of gametes
each gamete contains only one factor per trait
Mendel’s first law was based on?
examining one trait only
Difference between monohybrid and dihybrid cross?
monohybrid: involves study of a single characteristic
dihybrid: involves the study of two characteristics
Describe Mendel’s second law.
each member of 1 pair of alleles can combine with either member of another pair
What’s the name of Mendel’s second law?
law of independent assortment
The law of independent assortment refers to which of Mendal’s laws?
second
Definition of linkage?
the genes are located on the same chromosome
Definition of sex linkage?
a characteristic is controlled by a gene on an X chromosome
Does X or Y carry more genes?
X
Give two examples of sex-linked characteristics.
colour blindness,
haemophilia
What is haemophilia?
inability to clot blood
What’s colour blindness?
typically we see red, green and blue but being colour blind means inability to distinguish between red from green
For a female to be colour blind she needs?
two copies of the recessive allele
For a male to be colour blind he needs?
one recessive allele
Give two points on non-nuclear inheritance.
most of the DNA (and genes) in a cell is located in the nucleus
small loops of DNA in mitochondria and chloroplasts
Dihybrid cross crossing heterozygous x heterozygous gives what ratio?
9:3:3:1
Dihybrid cross crossing heterozygous x homozygous gives what ratio?
1:1:1:1
