Probability and Genetics

Trait
a characteristic that an organism can pass on to its offspring through its genes

Heredity
the passing of traits from parents to offspring

Genetics
the scientific study of heredity

Purebred
an organism that always produces offspring with the same form of a trait as the parent

Gene
a segment of DNA on a chromosome that codes for a specific trait

Allele
the different forms of a gene

Dominant allele
an allele whose trait always shows up in the organism when the allele is present

Recessive allele
an allele that is masked when a dominant allele is present

Hybrid
an organism that has two different alleles for a trait; heterozygous for a specific trait

Probability
the likelyhood an event will occur

Punnett square
a chart that shows all the possible combinations of alleles that can result from a genetic cross

Phenotype
an organism’s physical appearance, or visible traits

Genotype
genetic makeup of an organism or allele combinations

Homozygous
having two identical alleles for a trait (HH,hh)

Heterozygous
having two different alleles for a trait (Hh)

Codominance
both alleles of a gene are neither dominant or recessive (mix)

What is the difference between dominate and recessive alleles?
The dominant allele always shows up in an organism when the allele is present (stronger, shows up more). But a recessive allele is when it is masked or covered when a dominant allele is present.

Why do offspring have traits similar to those of their parents?
Because it is often the dominant genes that get passed down, so they won’t be covered by a recessive gene and will be similar to their parents.

What is the difference between a phenotype and a genotype?
The phenotype is an organism’s physical appearance, or visible traits. But the genotype is the genetic makeup of an organism or allele combinations.
Phenotype ex. : Blue eyes
Genotype ex. : BB

What is the difference between heterozygous and homozygous?
Heterozygous is having two different alleles for a trait (Hh)
Homozygous is having two identical alleles for a trait (HH, hh)

What is codominance? how is it different from the regular pattern of recessive and dominant traits?
Codominance is the inheritance pattern in which the alleles are neither dominant nor recessive. It is different because with dominant and recessive traits it has to be either or but for codominance it is neither (mix).

Explain how the inheritance of traits is controlled in organisms.
Individual alleles control the inheritance of traits. Some alleles are dominant , while others are recessive. The most dominant traits are the ones that control organism’s genes.

Can a short pea plant ever be a hybrid? Why or why not?
No, the short pea trait is recessive and the tall pea plant trait is dominant. This means that if the plant is a hybrid, it has to be a tall pea plant. The dominant traits “mask” the recessive traits. The plant take one trait from their mom and one from their dad. If either the mom or the dad was not a tall or hybrid pea plant then their kids would have to be tall be cause they would have one dominant and tall trait.

How is probability related to genetics?
Probability is used in genetics to determine the possibilities of offspring having a particular trait.

What type of letters do you represent dominant alleles?
Capital letters

A white cow is crossed with a red bull. The calf is neither white or red, but roan. Explain how this happens.
It’s called codominance. The alleles for white and red cannot overpower one another (in other words, the red gene is never dominant over the white gene but both can occur at the same time) to make the calf either white or red, so instead the coat coloration of the calf has red and white hairs that are intermingled with each other.

Meiosis
The process by which the number of chromosomes is reduced by half to form sex cells (sperm and eggs)

Messanger RNA
RNA that copies the coded message from DNA in the nucleus and carries the message into the cytoplasm

Transfer RNA
RNA in the cytoplasm that carries an amino acid to the ribosome and adds it to the growing protein chain

What is the chromosome theory of inheritance?
The genes are carried from parents to their offspring on chromosomes

What happens during each stage of meiosis to the cells and chromosomes?
Meiosis 1- Prophase 1: cell duplicates DNA Metaphase 1: Chromosome pairs line up next to each other in the center of the cell Anaphase 1: the pairs separate from each other and move to the opposite sides of the cell Telophase 1: 2 new cells are formed
Meiosis 2- Prophase 2: DNA does not replicate Metaphase 2: Chromosomes line up in the center of the cell Anaphase 2: the chromosomes separate from each other and move to the opposite sides of the cell Telophase 2: 4 cells have been produced, each ending up with half the number of chromosomes the parent cell had at the beginning of meiosis

What is the result of meiosis?
One parent cell produces 4 daughter cells. The daughter cells have half the number of chromosomes and the parent produces 2 more daughter cells that are genetically different.

What are some similarities and differences between meiosis and mitosis?
Similarities: Both have interphase, prophase, metaphase, anaphase, and telophase
Both processes are necessary for organisms to live/continue living
Differences: Meiosis produces 4 cells, mitosis produces 2
In meiosis, the 4 cells each have half the number of chromosomes the parent cell had at the beginning, in mitosis the cells are copies

How does the process of protein synthesis work?
During protein synthesis, the cell uses information from a gene on a chromosome to produce specific proteins.

What role does RNA play in the process of protein synthesis?
It copies, carries, and transfers the genetic code into the cytoplasm.

What is a mutation? How are some mutations helpful and how are some harmful?
A mutation is any change in a gene or chromosome. Helpful mutations are mutations that help the organism survive and/or reproduce and harmful mutations are mutations that inhibit the orgamism’s survival or reproduction. But some are neutral and are neither.