Lecture 10 Flashcards
Genetics involves mitosis or meiosis? and why?
meiosis b/c it involves sexual reproduction
Finish the sentence: Genetics is a branch of biology that deals with the way biological characteristics are ________.
inherited
A human genome consists of what range of genes?
20 000 - 25 000
Humans are identical in (what %) of the sequences of their genes
99.9%
Where are genes located?
on the chromosomes
A gene contains info needed to produce what?
a specific protein
Finish the sentence:
Proteins are the (what) of the cell
the work-horses
They affect events within cells and ultimately what?
organisms
they can play a role in determining traits
like what?
eye color, height, hair texture, blood type, etc.
What is an allele?
varieties of a gene pair
What is a locus in genetics?
a specific place on a chromosome where a gene is located
What does it mean the genes don’t share the same locus?
= These genes are not allelic to
one another
(they are not at the same location on their corresponding chromosomes)
True or false: Alleles contain the same info
FALSE,
-> Alleles govern the same
character but do not
necessarily contain the same
information
What is a dominant allele?
an allele that masks the presence of another allele
What is a recessive allele?
an allele whose presence can be masked by a Dominant Allele
Which allele is always a uppercase letter?
Dominant Allele = uppercase (B)
Recessive Allele = lowercase (b)
Name all 3 possible combinations of alleles:
- homozygous dominant
- heterozygous
- homozygous recessive
In a situation where B = brown eyes and b = blue eyes
which combination is which which letters?
- homozygous dominant = BB
- heterozygous = Bb
- homozygous recessive = bb
What is the phenotype expressed if it’s homozygous dominant (BB)?
Dominant phenotype expressed
(+ 2 dominant alleles present)
What does it mean if Bb?
heterozygous
= different alleles + Dominant phenotype expressed
What does it mean if bb?
Homozygous recessive
= 2 recessive alleles +
Recessive phenotype expressed
Difference b/w a phenotype and a genotype?
Genotype = combination of alleles
Phenotype = appearance of the characteristic
So in a situation of flower color, if the genotype is PP (homozygous dominant) then what would be the phenotype?
P = purple
phenotype is purple (appearance of the characteristic)
True or false: Phenotype does
not always reveal genotype
TRUE
Recessively inherited disorders occur only in individuals __________________
in individuals homozygous (recessive) for the allele
– ex. ff, pp, bb, yy, etc.
What do we call a carrier of the recessive allele (heterozygote)?
Someone who displays the dominant phenotype but is heterozygous for a trait
Dominantly inherited disorders occur in individuals _____________ _____________
in individuals homozygous (dominant) or heterozygous for the dominant allele
– ex. FF or Ff; BB or Bb …
What would it mean for people with ff genotypes (homozygous recessive) in a dominantly inherited disorder?
they would be “normal” (no disorder)
(+basically the reverse of a recessive disorder)
Name the person who was credited with developing a formal explanation of how characteristics were passed from one generation to the next
Gregor Mendel (1822-1884)
he was an Austrian priest
= “father of modern genetics”
He mainly worked on what plant?
pea plants
Why did he choose characteristics like flower color?
b/¢ it’s easy to observe and quantify
Careful mathematical analysis of the results gave rise to WHAT?
to Mendel’s PRINCIPLES (Mendel’s Model)
His model can be divided into how many concepts?
4 concepts
Add info on this concept:
1) There are alternative forms of genes
called alleles
= units that determine heritable traits
Add info on this concept:
2) For each characteristic, an organism has two genes, one from each parent.
They could be the same or different alleles