Unit 5: Hereditary

Codominance

________: Sometimes youll see an equal expression of both alleles.

female

A(n) ________ with one color blind- X is called a carrier.

Synapsis

________ involves two sets of chromosomes that come together to form a tetrad (a bivalent)

Traits

________ are influenced by one or more of your genes.

haploid

If a cell has only one set of chromosomes, we call it a(n) ________ cell.

new diploid

A parent will contribute a gamete with one set that will be paired with the set from the other parent to produce a(n) ________ cell, or zygote.

sexual reproduction

The mitochondria are always provided by the egg during ________, so mitochondrial inheritance is always through the maternal line, not the male line.

male

A(n) ________ has one X and one Y chromosome.

second meiotic division

The purpose of the ________ is to separate sister chromatids.

Polygenic inheritance

________: In some cases, a trait results from the interaction of many genes.

Punnett squares

________ are used to predict the results of a cross.

Mendel

________ crossed two true- breeding plants with contrasting traits: tall pea plants and short pea plants.

ovule

In plants the mitochondria are provided by the ________ and are maternally inherited.

Meiosis

________ is limited to sex cells in special sex organs called gonads.

Oogenesis

________ produces only one ovum, not four.

cell

A(n) ________ that has two sets of chromosomes is a diploid ________.

same chromosome

Since linked genes are found on the ________, they can not segregate independently.

spermatogenesis

During ________, four sperm cells are produced for each diploid cell.

Nondisjunction

________ can occur in** anaphase I** (meaning chromosomes dont separate when they should), or in anaphase II (meaning chromatids dont separate)

Humans

________ contain 23 pairs of chromosomes.

Non nuclear inheritance

________: Apart from the genetic material held in the nucleus, there is also genetic material in the mitochondria.

Nondisjunction chromosomes

________ failed to separate properly during meiosis.

Diploid

________ organisms usually have two copies of each gene, one on each homologous chromosome.

II

At telophase ________, a nuclear membrane forms around each set of chromosomes and a total of four haploid cells are produced.

anaphase II

During ________, chromatids of each chromosome split at the centromere, and each chromatid is pulled to opposite ends of the cell.

Barr body

A(n) ________ is an X chromosome that is condensed and visible.

sperm cells

If ________ are produced, then meiosis is called spermatogenesis.

Homologous chromosomes

________ are the same size and shape, and contain the same genes.

monohybrid cross

A(n) ________ occurs when two individuals are crossed and one gene is being studied.

Phenotypic plasticity

________ occurs if two individuals with the same genotype have different phenotypes since they are in different environments.

female cell

In every ________, one X chromosome is activated and the other X chromosome is deactivated during embryonic development.

organism

If a(n) ________ has two different alleles for a given trait, the ________ is heterozygous.

X chromosome

The ________ destined to be inactivated is randomly chosen in each cell.

chromosome

Individuals with Down syndrome have three- instead of two- copies of the 21st ________.

Sex cells

________ are haploid.

metaphase II

In ________, chromosomes move toward the metaphase plate.

identical alleles

When an organism has two ________ for a given trait, the organism is homozygous.

X inactivation

________ is the reason it is okay that females have two X chromosomes and males have only one.

Synapsis

________ is followed by crossing- over, the exchange of segments between homologous chromosomes.

females

In males, the gonads are the testes, while in ________ they are the ovaries.

Meiosis

________ is also known as gametogenesis.

Humans

________ have 23 pairs of homologous chromosomes.

homologous chromosomes

The ________ that make up each pair are similar in size and shape and contain the same genes in the same locations.

female

A(n) ________ has two X chromosomes.

Meiosis

________ is the production of gametes.

Homologous chromosomes

________ are two copies or versions of the same chromosome in a diploid cell or organism.

Meiosis

________ is likely to produce sorts of variations than is mitosis, which therefore confers selective advantage on sexually reproducing organisms.

Meiosis

________ actually involves two rounds of cell division: meiosis I and ________ II.

The three principles of genetics

the Law of Dominance, the Law of Segregation, and the Law of Independent Assortment

Mendel crossed two true-breeding plants with contrasting traits

tall pea plants and short pea plants

So far, we have looked at only one trait

tall versus short

Law of Dominance

One trait masks the effects of another trait

Law of Segregation

Each gamete gets only one of the copies of each gene

Law of Independent Assortment

Each pair of homologous chromosomes splits independently, so the alleles of different genes can mix and match

Twenty

two of the pairs of chromosomes are called autosomes

Most sex

linked traits are found on the X chromosome and are more properly referred to as "X-linked."

**Incomplete dominance (**blending inheritance)

In some cases, the traits will blend

Codominance

Sometimes youll see an equal expression of both alleles

Polygenic inheritance

In some cases, a trait results from the interaction of many genes

Non-nuclear inheritance

Apart from the genetic material held in the nucleus, there is also genetic material in the mitochondria

Meiosis actually involves two rounds of cell division

meiosis I and meiosis II

Meiosis I consists of four stages

prophase I, metaphase I, anaphase I, and telophase I