Genetics

The two major groups of specialized cells in your body are _______ and ________. Somatic cells and germ cells

______ cells, also called body cells, make up most of your body tissues and organs. Somatic cells

DNA is passed on to offspring by ____ ___. Germ cells

Gametes are ____ cells. sex

Each species has a characteristic number of ______ per cell. chromosomes

Chromosome number does not seem to be related to the _______ of an organism. complexity

Humans have ___ chromosomes in ___ pairs. 46, 23

Humans receive 23 chromosomes from the _____ and 23 from the _____. Mother, father

In humans, each pair of chromosomes is referred to as a ________ ____. Homologous pair

Homologous means……. Having the same structure

A number has been assigned to each homologous pair, ordered from _____ to _____. Largest to smallest

Chromosome pairs 1-22 make up your ______. autosomes

These chromosomes are not directly related to the sex of an organism. autosomes (1-22)

The two human sex chromosomes are __ and __. x and y

An organism with two X chromosomes is _____. female

An organism with one X chromosome and one Y chromosome is ____. male

X and Y chromosomes are not _______. homologous

The ____ chromosome is larger and contains numerous genes. X

______ _______ involves the fusion of two gametes that results in offspring that are a genetic mixture of both parents. Sexual reproduction

The actual fusion of an egg and sperm cell is called _______. fertilization

When fertilization occurs, the nuclei of the egg and sperm cell fuse to form one _____. nucleus

Egg and sperm cells only have half the usual number of ______. chromosomes

Body cells are ____, meaning that a cell has two copies of each chromosome. diploid

Gamete cells are _____, meaning that one cell has one copy of each chromosome. haploid

The sex of an individual is determined by the _____. Male (for humans)

Increasing the number of sets of chromosomes can give rise to a new _____. species

4 copies of each chromosome. A condition called tetraploidy

Germ cells in human reproductive organs undergo _____ to form gametes. meiosis

______ is a form of nuclear division that divides a diploid cell into haploid cells. meiosis

______ is a type of cell division that occurs in body cells. Mitosis

What are some of the differences between mitosis an meiosis? In mitosis, DNA is copied once and divided once. In meiosis, DNA is copied once but divided twice. In mitosis, daughter cells are genetically identical to the parent cell. Meiosis makes genetically unique haploid cells from a diploid cell. Mitosis is used for growth, development, and repair. Takes place throughout life. Meiosis, however, takes place only at certain times. Mitosis is involved in asexual reproduction, meiosis is involved in sexual reproduction.

Where are germ cells located in the human body? Ovaries and testes What is the difference between an autosome and a sex chromosome? Autosomes, chromosomes 1-22, are not directly related to the sex of an organism.

Is the cell that results from fertilization a haploid or diploid cell Is the cell that results from fertilization a haploid or diploid cell? Explain. Each cell has only one copy of each chromosome. It takes the combination of an egg and sperm cell to make the 46 human chromosomes…..so haploid.

Does meiosis or mitosis occur more frequently in your body? Mitosis, it is responsible for growth, development, and repair. Meiosis is responsible for reproduction.

_______ is a form of nuclear division that creates four haploid cells from one diploid cell. Meiosis Meiosis _______ chromosome number and creates genetic _________. reduces,diversity

Each half of a duplicated chromosome is called a ________. Chromatid ______ ______ are the duplicated chromosomes that remain attached by the centromere. Sister Chromatids

______ ______ are divided during meiosis I. ____ ______ are not divided until meiosis II. Homologous chromosomes Sister chromatids

Before meiosis begins, _______ has already been copied. DNA What are the 4 stages of meiosis I? Prophase I Metaphase I Anaphase I Telophase I

Identify the phase in meiosis I. The nuclear membrane breaks down centrosomes and centioles move to opposite sides of the cell. Spindle fibers assemble Homologous chromosomes pair up Prophase I

Identify the phase in Meiosis I Homologous chromosome pairs are randomly lined up along the middle of the cell by spindle fibers. Metaphase I

Identify the phase in Meiosis I Paired homologous chromosomes separate and move to opposite sides of the cell. Anaphase I

Identify the phase in Meiosis I The nuclear membrane forms, the spindle fibers disassemble, and the cell undergoes cytokinesis. Telophase I

Identify the phase in Meiosis II The nuclear membrane breaks down, centrosomes and centrioles move to opposite sides of the cell, spindle fibers assemble. Prophase II

Identify the phase in Meiosis II Spindle fibers align the 23 chromosomes at the cell equator Metaphase II

Identify the phase in Meiosis II The sister chromatids are pulled apart from each other and move to opposite sides of the cell. Anaphase II

Identify the phase of Meiosis II Nuclear membranes form around each set of chromosomes at opposite ends of the cell, spindle fibers break apart, the cell undergoes cytokinesis, and four haploid cells are produced. Telophase II

What is the major difference between Metaphase I and Metaphase II? In metaphase I, pairs of homologous chromosomes line up at the equator. In metaphase II, the chromosomes are not paired.

What is the major difference between Anaphase I and Anaphase II? Sister chromatids remain together in Anaphase I but separate in Anaphase II.

___________ is the production of gametes. Gametogenesis

The sperm cell’s main contribution to an embryo is ____________. DNA

Distinguishing characteristics that are inherited, such as eye color, leaf shape, and tail length. Traits

The study of biological inheritance patterns and variation in organisms. Genetics

The groundwork for genetics was laid in the middle 1800’s by an Austrian monk named ________ ________. Gregor Mendel

What three key choices did Mendel make in his experiments that helped him develop his laws of inheritance? Control over breeding Use of purebred plants Observation of “either-or” traits that appeared in only two alternate forms

Why did Mendel choose pea plants for his experiments? They reproduce quickly and it is easy to control fertilization

Genetic Uniformity. The offspring inherit all of the parent organisms’ characteristics. purebred

What seven traits for pea plants did Mendel observe? Pea shape Pea color Pod shape Pod color Plant height Flower color Flower position

In genetics, the mating of two organisms is called a … cross

Mendel called the very first purebred generation of pea plants the ________, or ________ generation. Parental or P

Mendel called the offspring of the parental generation the ______ ______ generation. First filial

Mendel called the generation after the first filial generation the ________ generation.

What happened with Mendel’s F₂ generation? Plants were produced with both purple and white flowers, the entire F₁ generation produced purple flowers, the trait for white flowers had not disappeared; it had been masked.

What pattern did Mendel notice in the F2 generation? Similar ratios were noticeable

What conclusions did Mendel draw from his observations? Traits are inherited as discrete units. Organisms inherit two copies of each gene, one from each parent. Organisms donate only one copy of each gene in their gametes.

A piece of DNA that provides a set of instructions to a cell to make a certain protein. Gene

Any of the alternative forms of a gene that may occur at a specific locus. Allele

Your cells have ______ alleles for each gene. Two

A term used to describe two of the same alleles at a specific locus. Homozygous

A term used to describe two different alleles at a specific locus. Heterozygous

All of an organism’s genetic material. Genome

This term refers to the genetic makeup of a specific set of genes. Genotype

The physical characteristics, or traits, of an individual make up its ________. Phenotype

The allele that is expressed when two different alleles are present. Dominant

The allele that is expressed when two copies are present. Recessive

A grid system for predicting all possible genotypes resulting from a cross. Punnett Square

What do the letters on the axes of the punnett square represent? The condition of alleles from each parent.

A cross that examines the inheritance of only one specific trait. Monohybrid crosses

FF Homozygous Dominant

ff Homozygous Recessive

Ff Heterogygous Parent

A cross between an organism with an unknown genotype and an organism with the recessive phenotype. Test-cross

From an FF x ff cross, what percent of offspring would have purple flowers? (Purple being dominant) 100% F f Ff

From an Ff x Ff cross, what percent of offspring would have purple flowers? (purple being dominant) 75% F f FF Ff

From an ff x Ff cross, what percent of offspring would have purple flowers? (purple being dominant) 50% f F Ff ff

Crosses that examine the inheritance of two different traits. Dihybrid crosses

Allele pairs separate independently of each other during gamete formation, or meiosis. Different traits appear to be inherited separately. The Law of Independent Assortment, The Second Law of Genetics

The likelihood that a particular event will happen probability

Number of ways a specific even can occur Number of total possible outcomes Probability

Why does the expected genotypic ratio often differ from the expected phenotypic ratio resulting from a monohybrid cross? Multiple genotypes can cause the same phenotype. The homozygous dominant genotype and the heterozygous genotype yield the same phenotype in simple dominant-recessive cases

What is the major advantage of sexual reproduction? It gives rise to a great deal of genetic variation

Genetic variation within species results largely from The independent assortment of chromosomes during meiosis and the random fertilization of gametes

The exchange of chromosome segments between homologous chromosomes during prophase-I of meiosis-I Crossing over

Any mixing of parental alleles recombination

Genes located close together tend to be inherited together. Genetic linkage

How does crossing over contribute to genetic diversity? Crossing over makes new combinations of maternal and paternal genes

The word meiosis comes from a Greek word meaning “to diminish”, or make less. How does this word’s origin relate to its meaning? Meiosis is a reductive process that diminishes, or reduces, the amount of DNA. It begins with a diploid cell and ends with haploid cells.

A fruit fly has diploid cells with 8 chromosomes A fruit fly has diploid cells with 8 chromosomes. Explain how many chromosomes are in its haploid gametes 4 chromosomes, because meiosis results in haploid gamete cells, with only one set of chromosomes.

Many human genetic disorders are caused by _______ genes. autosomal

For a genetic disorder to be caused by a recessive allele, ____ _______ must be present for a person to have the disorder. Two copies

An individual who does not show disease symptoms but can pass on the disease causing allele to offspring. Carrier

Genes located on the sex chromosome Sex-linked genes

Males (XY) have only one copy of each type of sex chromosome Males (XY) have only one copy of each type of sex chromosome. Because of this, males express ____ alleles on both chromosomes, even if all alleles are _______. All, recessive

In female mammals, this is when one of the two X chromosomes is randomly turned off. X-chromosome inactivation

Why are males more likely than females to have sex-linked genetic disorders? All sex-linked genes, even recessive ones, are expressed in males.

How are autosomal traits, including recessive genetic disorders, related to Mendel’s observation of heredity? Two copies of autosomal genes affect phenotype, as observed in all of Mendel’s crosses

How might a scientist determine whether a trait is sex-linked by observing the offspring of several genetic crosses? If more males than females have a particular phenotype, the trait is probably sex-linked

Why are female calico cats white, black, and orange, while male calico cats are white and orange or white and black? Males cats have only one X chromosome.

Does dominance mean that one allele defeats the other? No. The dominant allele usually codes for a specific protein. The recessive allele codes for a variation of the protein that has little or no effect.

Neither allele is completely dominant or completely recessive. Incomplete dominance

What are two examples of incomplete dominance? The 4 o’clock plant. When plants that are homozygous for red flowers are crossed with plants that are homozygous for white flowers, the offspring have pink flowers. The color of betta fish. When a green betta fish is crossed with a steel blue fish, the result is a royal blue betta fish.

The expression of both alleles of a gene The expression of both alleles of a gene. Neither allele is dominant or recessive. codominance

Provide an example of codominance. A flower that has red and white splotches. The human ABO blood type.

Traits produced by two or more genes. polygenic

A lack of pigment in skin Albinism

In what ways may environment interact with genotype? For sea turtles, eggs that mature in warmer temperature develop into females. Cooler temperatures result in males. Amount of available nutrients during developmental stages of life may affect size

What two scientists first described gene linkage? William Bateson and RC Punnett

Traits that are inherited together. Linked traits or gene linkage