Intro into genetics study guide

What is a gamete?

- Gametes are reproductive cells that unite during sexual reproduction to form a new cell called a zygote. - Male gametes are sperm and female gametes are ova (eggs). In seed bearing plants, ​pollen​ is the male sperm producing gametophyte. - Gametes are produced by a type of cell division called ​ meiosis​ -They are ​ haploid, contain only one set of ​chromosomes​ - When the haploid male and female gametes unite in a process called fertilization, they form what is called a zygote. The zygote is ​diploid​ and contains two sets of chromosomes.

What is the difference between mitosis and meiosis?

- Mitosis is a process of cell division that results in two genetically identical daughter cells developing from a single parent cell.Mitosis is used by single-celled organisms to reproduce - division of a ​germ cell​ (such as sperm and egg) involving two fissions of the nucleus and giving rise to four ​gametes​, or sex cells, each possessing half the number of chromosomes​ of the original cell.. Meiosis is found in sexual reproduction of organisms.

How many alleles for the height gene does a pea plant gamete have?

2

What happens to the F​1 generation generation if a heterozygous tall pea plant is crossed with a homozygous short pea plant?

50% of the F​1​ generation will be (Tt) yields tall plants which and 50% will be (tt) which yields short plants.

What are gametes?

A Gamete is a mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote. Example- egg and sperm.

What are diploids?

A diploid cell is a ​cell​ that contains two sets of ​ chromosomes​. One set of chromosomes​ is donated from each parent. - For humans this equation would be 2n=46.

What is a hybrid?

A hybrid is a offspring of crosses between parents with different traits.

What are genotypes?

A person's genotype refers to the types of genes he or she has for a particular inheritable trait. Genotypes determine which characteristics an individual will express, for example: whether they have freckles or not

What is a tetrad?

A tetrad is a structure containing 4 chromatids that form during meiosis.

What are alleles?

Alleles are different forms of a gene. They can be dominant or recessive. Some characteristics, such as eye color and the shape of the earlobe, are controlled by a single gene. These genes may have different forms.

Explain how allowing the generation F​1​ to self- pollinate in producing the F​2 ​generation allowed Mendel to reach his conclusion about inheritance.

Allowing the F​1 pea plant to self pollinate caused the recessive phenotype to reappear in the F​2​ generation. Self-pollination of the F​1​ plants also allowed the 3:1 phenotype ratios to occur, supporting Mendel‛s theory. Self pollination showed that traits controlled by the recessive alleles could reappear in the F​2​ generation.

What are phenotypes?

An individual's phenotype consists of the traits we can observe. These can include features of appearance, behavior, metabolism, or anything else we can detect. Humans have appearance phenotypes, too; for example, your height and your eye color are both phenotypes controlled, at least partly, by your genes

What are regulatory genes?

Any gene that REGULATES control over the expression of another gene. A regulatory gene may "silence" another gene from expressing its dominant trait. For example the Manx cat has no tail bc it has a regulatory gene that silences the gene that expresses the tail.

If a pea plant‛s alleles for height are ​tt​, what could be said about the parents?

Both carried the ​tt​ recessive allele. They both had heterogeneous alleles for height ​(Tt).

What are chromatids?

Chromatids are 1 of 2 identical "sister" parts of a duplicated chromosome.

When do chromosomes form tetrads?

Chromosomes form Tetrads during meiosis in Prophase I.

What is codominance?

Codominance occurs when both phenotypes produced by both alleles are clearly expressed. Such as when a red flower crosses with a white flower and instead of having either white or red flowers the flowers are white with red spots.

What are daughter cells?

Daughter cells are cells that are produced as a part of the process of cell division. Depending on whether cells are dividing in ​mitosis​ or ​meiosis​, the daughters can be genetically identical to the parent cell or they may be different.

Explain the principle of independent assortment?

Describes how different genes independently separate from one another when reproductive cells develop. Independent assortment of genes and their corresponding traits was first observed by Gregor Mendel in 1865 during his studies of genetics in pea plants

Which principle explains why a female bison and male bison that are both heterozygous for normal skin pigmentation (Aa) produce an albino offspring (aa).

Dominance and segregation explain why the heterozygous (Aa) parents can have an albino offspring.

How are gametes produced?

Gametes are produced by a type of cell division called ​ meiosis​. They are ​haploid​,meaning that they contain only one set of ​chromosomes​. When the haploid male and female gametes unite in a process called fertilization, they form what is called a zygote. The zygote is ​diploid and contains two sets of chromosomes.

What are gene maps?

Gene maps are a graphic representation of the order of genes within chromosomes by means of detailed analysis of the DNA. They are based on the frequencies of crossing over.

What are linked genes?

Genes that are inherited together with the other gene(s) as they are located on the same chromosome.

What does heterozygous mean?

Heterozygous refers to having two different ​ alleles​ for a single trait. - Organisms have two alleles for each trait. When the alleles of a pair are heterozygous, one is dominant and the other is recessive. Using the previous example, round seed shape (R) is dominant and wrinkled seed shape (r) is recessive. Round: (RR)or (Rr), Wrinkled: (rr).

What does homozygous mean?

Homozygous refers to having identical ​alleles​ for a single trait.

Explain why Thomas Hunt Morgan used fruit flies in his studies.

Hunt Morgan used fruit flies in his experiment because fruit flies produce large numbers of offspring.

Explain how a trait might seem to "disappear" for a generation, and then "reappear" in the following generation.

If all of the individuals in a generation receive one dominant allele and one recessive allele, then they would all show the dominant trait. If they are bred, then they will pass on the dominant allele to some of their offspring and the recessive allele to the others. Offspring receiving 2 recessive alleles will show the recessive trait, so it will reappear.

What happens if 2 genes are far apart on a chromosome?

If they are far apart, they are less likely to be inherited together.

What is incomplete dominance?

Incomplete dominance is occurs when one allele is not completely dominant over the other allele. In incomplete dominance, the heterozygous phenotype lies somewhere between the 2 homozygous phenotypes. For example if you cross a red and white flower and the cross yields pink flowers.

How is meiosis I different from mitosis?

Meiosis I produces 2 haploid daughter cells, but mitosis produces 2 diploid daughter cells.

What is meiosis?

Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information. These cells are our sex cells - sperm in males, eggs in females. Meiosis can be divided into nine stages. These are divided between the first time the cell divides (meiosis I) and the second time it divides (meiosis II)

Why did Mendel choose pea plants to study genetics?

Mendel chose pea plants because they can produce many offspring, they have traits that come only in 2 forms, and crosses between the plants can be controlled easily.

What are multiple alleles?

Multiple alleles have more than 2 variations of a gene. An example of multiple alleles is human blood types. People can have A, B, AB or O blood types.

What symbol represents the number of chromosomes in a gamete?

N" represents the number of chromosomes in a gamete.

A tall plant (​TT​) is crossed with a short plant ​ (tt)​. If the tall F​1​pea plants are allowed to self pollinate, the offspring what will happen?

P Generation - 100% of offspring will be tall. F1 - 75% will be tall and 25 % will be short

What are polygenic traits?

Polygenic traits are traits that are said to be dominated by 2 or more genes. Polygenic traits often show a wide range of phenotypes. The variety of skin color in humans comes about partially bc more than 4 different genes control this trait

What is the P generation?

The "p" stands for ​parental​. Parental generation is the first ​generation​ involving two individuals that are mated to foresee or analyze the ​genotypes​ of their offspring​.

What is the F​1 ​generation?

The F1 generation is the first generation of offspring produced by a set of parents. The 'F' in F1 stands for 'filial.' So in short, F1 means 'first filial generation'.

What is the F​2 ​generation?

The F2 generation is the result of a ​cross​ between two F1 individuals (from ​F1 generation) ​

What happened to the F​1 ​generation when Gregor Mendel crossed a tall pea plant with a short plant?

The F​1 ​generation inherited one allele from each parent.

Explain why short plants reappeared in the F​2​ generation if in the P generation, a tall plant was crossed with a short plant.

The allele for both heights segregated when the F​1​ plants made gametes.

What is the end result of meiosis?

The end result is haploid cells.

What is the principle of segregation?

The principle of segregation states that during gamete formation, the alleles for each gene segregate from each other, so that each gamete carries only one allele for each gene.

If a pea plant that is heterozygous for round, yellow peas (RrYy) is crossed with a pea plant that is homozygous for round peas but is heterozygous for yellow peas (RRYy), how many different PHENOTYPES are their offspring expected to show?

There will only be 2 phenotypes because all are going to be round (they are all RR or Rr which yields round shape) There is no rr which yield wrinkled shape. The only variant will be if they are yellow or green (YY and Yy yield yellow and yy yield green).

If a breed of chicken show codominance for feather color, one allele codes for black feathers and another for white feathers, what will the feathers of heterozygous chickens of this breed be?

They will be speckled bc of codominance. Neither the black or white dominates

Why did Gregor Mendel remove the male parts of flowers of some plants?

To control the crosses between the plants

How can the principles of probability be used?

Used to predict the traits of offspring of genetic crosses.

What can you apply Mendel‛s principle of genetics to?

You can apply Mendel‛s principles to all organisms.

What happens to 2 genes if they are on the same chromosome and rarely assort independently?

You can infer that they are probably close together.