exam 3 ch 11

How many homologous pairs are there?

23 pairs

HOMOLOGOUS CHROMOSOMES

A pair of chromosomes that both contain the same genes. In a diploid cell, one chromosome in the pair is inherited from the mother, the other from the father.

Gene

A section of DNA that may contain the instructions for assembling amino acids together into a polypeptide chain. There may be several alternate versions of the instructions.

Chromosome

A single, long DNA molecule (wrapped around special proteins) that contains the individual instructions for many different proteins.

Can you think of a situation when genes would not be inherited in pairs (*hint: think of sex determination)?

A situation when genes would not be inherited in pairs is shown when looking at the sex chromosomes X and Y. For example, males inherit one X chromosome from their mother and one Y chromosome from their father, thus only having one copy of the chromosomes, and thus genes, of X and Y.

MEIOSIS

A specialized type of nuclear division that generates genetically unique haploid gametes.

DOMINANT ALLELE

An allele that can mask the presence of a recessive allele

DOMINANT ALLELE

An allele that can mask the presence of a recessive allele.

RECESSIVE ALLELE

An allele that reveals itself in the phenotype only if a masking dominant allele is not present

Allele

An alternate version of a gene.

CARRIER

An individual who is heterozygous for a particular gene of interest, and therefore can pass on the recessive allele without showing any of its effects.

PHENOTYPE

The visible of measureable features of an individual.

Given that most chromosomes occur in homologous pairs, do most genes also occur in pairs?

Yes, since chromosomes are long stretches of DNA containing gene sequences

At the start of meiosis, each homologous pair of chromosomes consist of _____.

two chromosomes made of two sister chromatids each

Why is it advantageous for an organism to have two copies of every gene?

Since genes are inherited in pairs, it provides, in essence, a backup system where if one gene is mutated and nonfunctional, the other normal gene may be able to compensate for the loss.

GENOTYPE

The particular genetic makeup of an individual.

Where does each member of the gene pair come from?

You inherit one chromosome (and thus genes) from your mother, and one chromosome (and thus genes) from your father.

Which characteristics can differ between a gene and its mutated allele? Choose all that apply.

a. Nucleotides b. Amino acids c. Shape d. Length

What is the probability their child will not have a dimpled chin AND will not be able to tongue-roll?

1 out of 16

What is the probability their child will be homozygous DD?

25%

What is the probability their child will be able to tongue-roll?

75%

ZYGOTE

A cell that is capable of developing into an adult organism. The zygote is formed when an egg is fertilized by a sperm.

PUNNETT SQUARE

A diagram used to determine probabilities of offspring having particular genotypes given the genotypes of the parents.

RECESSIVE ALLELE

An allele that reveals itself in the phenotype only if a masking dominant allele is not present.

EMBRYO

An early stage of development reached when a zygote undergoes cell division to form a multicellular structure.

RECOMBINATION

An event in meiosis during which maternal and paternal chromosomes pair and physically exchange DNA segments.

Draw the chromosomes of the cell right before it enters meiosis. What process has happened at this step?

DNA replication

HAPLOID

Having only one copy of every chromosome.

DIPLOID

Having two copies of every chromosome.

HETEROZYGOUS

Having two different alleles

HOMOZYGOUS

Having two identical alleles

Draw the homologous chromosomes during metaphase I. a.What genetic material is separated here (homologous chromosomes or sister chromatids)?

Homologous chromosomes

Given that this diploid cell will undergo meiosis and give rise to gametes, (egg or sperm cells), where in the body would you expect this cell to be located?

In the ovaries or testis.

Recombinantion and independent assortment ____________ the amount of genetic diversity seen among haploid sperm and egg cells.

Increases

Are the two members of each pair of chromosomes in this cell identical to each other in nucleotide sequence? Why

No, although they contain the same genes, one chromosome comes from the mother and one comes from the father, thus the genes may be slightly different.

In many organisms, including humans, chromosomes occur in homologous pairs; where does each member of the pair originate?

One chromosome comes from your mother and the other comes from your father.

Protein

One or more chains of amino acids connected in a specific order and taking on a particular shape that is functional.

GAMETES

Specialized reproductive cells that carry one copy of each chromosome (that is, they are haploid). Sperm are male gametes; eggs are female gametes

INDEPENDENT ASSORTMENT

The principle that alleles of different genes are distributed independently of one another during meiosis.

PHENOTYPE

The visible or measureable features of an individual. [GENOTYPE] The particular genetic makeup of an individual.

one of the mutations that causes CF, discussed in the text, results from the deletion of ______ in the CFTR gene, which causes the _______ of an amino acid in the CFTR protein, thus making it nonfunctional.

an entire codon / omission

True or False: In terms of size, from largest to smallest, the units of inheritance go from chromosome, to gene, to allele.

false

True or False: at the end of meiosis II, each cell has more genetic information than the original cell at the start of meiosis I.

false

Meiosis ____ the number of chromosomes in a person's body cells to create _____ gametes.

halves / haploid