L6: PATTERNS OF INHERITTANCE Flashcards
What are genes?
A segment of DNA within the chromosome.
What is the basic unit of genetic info for a specific character?
Genes
What is a genes fuction?
it is the code for proteins
What is a chromosome?
A large strand of DNA
How many chromosomes are in one of our cells? pairs?
46 chromosomes, 23 pairs
T/F: most of our cells contain exactly the same set of genes
True.
What is significant about our sperm and egg cells in regards to genes?
Sperm and egg cells contain only one of the two copies of gene
Whats an alternative version of a gene called?
Alleles
What is the basic unit of inheritance?
Gene
Homozygote
an individual who carries two copies of the same allele
Heterozygote
an individual that carries different alleles
How did different alleles arise?
From mutation
What is a mutation?
Change in DNA that makes up a gene
Mutation can be three things:
- harmful
- benefical
- neutral
What is a genotype?
the genetic makeup of an organisim
What is a phenotype?
the observable physical characteristics
From the following, which is the phenotype vs the genotype… Short hair and LL homozygote :
Short hair = phenotype
LL homozygote = genotype
Dominant alleles are represented by ….
capital letters
Recessive alleles are represented by …
lowercases
What is believed in the blending inheritance theory?
offspring should have a phenotype intermediate between those of their parents
Whats a basic example proving the blending inheritance theory isn’t true?
-eye colour
- skips generations in humans
Who disproved the theory of blended inheritance?
Gregor Mendel
How did Mendel disprove the theory of blended inherritance?
- he used true-breeding pea plants
- crossed the pea plants - they were purple
- then self pollinated F1 plants to produce F2 plants
What does true breeding mean?
When parents are self - pollinated the offspring are identical to the parents
What happened when Mendel pollinated F1 plants to produce F2 plants ?
Some came out purple and some came out white
What theory did Mendel come up with to conclude his experiment?
The particulate theory of inheritance
What tool did Mendel use to support his findings ?
A Punnett square
What 5 things did Mendel conclude about inheritance?
- alleles cause variation
- offspring inherit one copy of the gene from each parent
- alleles separate into different gametes
- gametes fuse without regard which allele they carry
- alleles can be dominant or recessive
What is Mendels 1st law?
- the law of segregation
- state that two copies of each gene separate during meiosis, and end up in different gametes
What is Mendel’s 2nd law?
- independent assortment
- states to form gametes alleles for one trait combine randomly with alleles for other traits
How do you get 4 different types of gametes?
-meiosis 1 - anaphase
- depends on the different combinations that the homologous pairs line up on the metaphase plate
Incomplete dominance occurs when..
heterozygote phenotype that is intermediate between those of the two homozygotes
Most characters are controlled by …
multiple genes
An example of characters being controlled by multiple genes:
- human skin colour
- skin colour in humans is controlled by three genes that have equal effects
