ITP
_ the genetic difference between individuals.
Genetic variation
In humans, genetic variation begins with an _
egg
The egg and the sperm each contain _ chromosomes.
23 chromosomes
meaning of DNA?
Deoxyribonucleic Acid
_ are long strings of genetic material known as deoxyribonucleic acid (DNA).
chromosomes
helix-shaped molecule
DNA or Deoxyribonucleic Acid
_ actual carrier of hereditary traits.
Genes
_ specific version of a gene.
Allele
_ physical characteristics
Phenotype
_ genetic makeup
Genotype
When someone has two copies of the same allele _
homozygous
When someone has a combination of alleles for a given gene _
heterozygous
_ is a tool used to predict how genes will interact
Punnett square
how many weeks of Germinal?
1-2 weeks
how many weeks of Embryonic?
3-8 weeks
how many weeks of Fetal?
9-40 weeks
_ occurs when sperm fertilizes an egg and forms a zygote.
Conception
A _ begins as a one-cell structure that is created when a sperm and egg merge
Zygote
_ During the first week after conception, the zygote divides and multiplies, going from a one-cell structure to two cells, then four cells, then eight cells, and so on.
Mitosis
_ it travels down the fallopian tubes and implants itself.
Embryo
_ structure connected to the uterus that provides nourishment and oxygen.
Placenta
Basic structures of the embryo start to develop into areas that will become the _ _ and _.
head, chest, and abdomen.
During the embryonic stage, the _ _ to _ and organs form and begin to function.
the heart begins to beat
When the organism is about nine weeks old, the embryo is called a _.
Fetus
From _ weeks, the sex organs begin to differentiate. At about 16 weeks, the fetus is approximately 4.5 inches long.
9-12 weeks
_ Weeks: the brain continues to grow and develop, nearly doubling in size
16-18 weeks
_ Weeks: the fetus is almost ready for birth and weighs about 6 pounds and is about 18.5 inches long
36 weeks
_ Weeks: all of the fetus's organ systems are developed enough that it could survive outside the mother's uterus without many of the risks associated with premature birth.
37 weeks
_ Weeks: The fetus continues to gain weight and grow
40 weeks