Post on 17-Dec-2015
No one really knows what determines the number of chromosomes in an organism,
though related species tend to have similar chromosome numbers. This is because
chromosomes may split or combine during evolution and speciation. While humans have 46, other great apes have 48. It is
important to remember that the chromosome number has nothing to do with how "advanced" a species is. Horses, dogs, and several species of ferns have more than
we do.
You get 23 chromosomes from each parent. 1 of the 23 chromosomes determines whether you are male or female. The other 22 chromosomes (Autosomal DNA) pretty much determine your genetic profile. You get Autosomal DNA 50-50 from both parents.
The two germ cells, male sperm and female egg, have chromosomes with DNA in them. When the germ cells get fused they form a zygote and this
process is responsible for transferring the character from parent to offspring.
Genetics is all about PROBABILITY. There is a very high percentage that you will because
brown eyes is a dominant trait. But then again you should also look at your
grandparents, aunts and uncles, because anyone in your gene pool has had an affect
on what color eyes you will have. But in most cases, yes, you will most likely have
brown eyes.
All the traits you are going to have in your lifetime you have at the time of conception and is outlined in your genetic map (DNA). However, not all traits are visible at birth.
Most traits are “time released” meaning that they present themselves at various stages of
growth and development.
The sex chromosomes carry genes that determine whether a person is male or
female. The sex chromosomes are the only chromosome pair that do not always match.
Since both of a female’s sex chromosomes are X chromosomes, all eggs carry one X chromosome. Males, however, have two
different sex chromosomes. Therefore, half of a male’s sperm cells carry an X chromosome, while half carry a Y
chromosome.
When the male sperm and female egg get fused during fertilization the phenomena of CROSSING OVER takes place which mix all the characters of the parents and the child
gets a combination of both of them.
You get 23 chromosomes from each parent. The 22 chromosome pairs with the
Autosomal DNA pretty much determine your genetic profile. Your Autosomal DNA is 50-50
from both parents.
The 23rd chromosome pair, one from each parent, determines your sex and are made up of Y & Mitochondrial DNA. Y goes from
father to son only. Mitochondrial goes from mother to both sons and daughters but only the daughters pass it on to their children.
A person can carry an allele (code) for a particular gene (trait) that is not visibly
present in them. But, because it is part of their DNA they can pass it on to their
offspring and it may become visible in their offspring or even future generations of
offspring within their family.
Because children inherit alleles (codes) for genes (traits) from their mother and father, children often look like both of their parents. If a child resembles one parent over another
it is because one parent may have a stronger (dominant) gene pool.
All the traits you are going to have in your lifetime you have at the time of conception and is outlined in your genetic map (DNA).
Most traits are “time released” and will present themselves at various stages of
growth and development.
Background Knowledge
• Gregor Mendel developed the basic principles of genetics that are still used today in our current study of heredity.
• Using pea plants, observing multiple generations and thousands of offspring, Mendel determined that most traits are controlled by genes with two alleles.– Dominant – Recessive
Lab Objective
• How frequently do certain dominant and recessive phenotypes occur in humans?
• PHENOTYPE – AN ORGANISM’S PHYSICAL APPEARANCE, OR VISIBLE TRAITS.
Question / Hypothesis
• Does the dominant form of a trait always occur more often within a population than the recessive form?
General Procedure
• Read all instructions for this activity before you begin your work.
• Collect and Analyze Data.– Record your phenotype for each trait in
the data table.– Report your data.– Record the “class” data for each trait in
the table.
Data Table
Trait2nd
D2nd
R3rd
D3rd
R4th
D4th
R6th
D6th
R7th
D7th
R
TEAMD
TEAMR
Tongue Rolling 31 13 35 6 28 4 35 8 26 7 155 38
Polydactyl 0 44 2 39 0 32 1 42 0 33 3 190
Eye Wink 40 4 30 11 23 9 38 5 26 7 157 36
Mid-Digital Hair 14 31 9 32 18 14 24 19 7 26 72 122
Dimples 13 31 14 27 15 17 28 15 14 19 84 109
Hairline 17 27 12 29 12 20 18 25 14 19 73 120
Earlobes 35 9 30 11 24 8 31 12 25 8 145 48
Interlocking Finger 33 11 23 18 20 12 32 11 25 8 133 60