CHAPTER 12 VOCABULARY

Diploid - this is the number of chromosomes found in somatic (soma = body) or non-sex cells, this number will consist of pairs of chromosomes. It is sometimes given as 2n

(2 = pair!) One chromosome of each pair comes from one of the parent's gamete and the other chromosome comes from the other parent's gamete. A human kidney cell has a diploid number of 46 chromosomes. 23 pairs of chromosomes = 46, each pair has one chromosome from one parent's gamete. When somatic cells divide they do so by mitosis and cytokinesis.

Haploid - this is the number of chromosomes found in sex cells/ gametes these are either the sperm or egg, this number represents only one member of each chromosome pair. It is sometimes given as n. In order for this to happen a diploid cell in a man's testis or a woman's ovary will ultimately form gametes by doing meiosis and cytokinesis. The human haploid number of chromosomes in the sperm or egg is 23 chromosomes. The meiotic stages go through a pattern similar to mitosis and are prophase 1, metaphase 1, anaphase 1, telophase 1, prophase 2, metaphase 2, anaphase 2 and telophase 2. Since cytokinesis occurs during both telophases this results in 1 diploid cell becoming 4 haploid cells.

Gene - portion of a DNA molecule (chromosome) that is the information for the

synthesis of a specific protein. Recall that it is the sequence of DNA nucleotides (ATCG) that ultimately controls the production of a protein during protein synthesis. There are thousands of different genes per DNA molecule. Each chromosome/DNA molecule contains unique genes not found on any other chromosome. Genes exist for such things as;eye lash length, blood type, insulin production, hemoglobin, skin pigmentation etc..

CHAPTER 13 VOCABULARY

Allele - alternate versions of a gene. Such as; short eye lash, type A blood,

normal insulin production, sickle cell anemia hemoglobin, albino pigmentation etc..

Multiple Alleles - when there are more than two choices of alleles, each individual still only has two (one per chromosome) but there are more than just 2 possibilities. An example is blood type. The alleles are A, B and O, but a given individual only will have two at a time, i.e. AA or AO.

Multiple Gene inheritance - When more than one gene contributes to one phenotype. These phenotypes typically show a wide range of possibilities, not just one or the other. Human height, amount of natural skin pigmentation, eye color, the variety of hair colors all are examples.

Multi Factor inheritance- when the environment also influences the phenotype, such as height, weight, personality, allergies are examples.

Dominant - many (not all) alleles will either dominate or not over the other allele. We have some idea why certain alleles are dominant or recessive, we have just figured some of them based on the pedigree and their phenotype. The biochemical reasons for dominance/recessiveness are much too complicated for us to worry about. For example when a persons genotype for eye color is brown and blue it turns out that their phenotype is always brown, therefore brown is dominant over blue. We often pick the first letter of the dominant allele to represent this gene. In this case B would represent brown and b represents blue. It just so happens they both begin with a "b". For wavy hair versus straight hair, wavy is dominant, so the two symbols are W and w.

Recessive - In the above example blue and straight are recessive.

Genotype - a list of an organisms alleles for a gene/s. Such as; LL or Ll or ll.

Phenotype - the physical expression of a genotype, if the genotype is LL this person would have long eye lashes. Long eye lashes is their phenotype.

Homozygous - When the genotype is made up of the same (homo = same, zygous= pair) alleles. BB or bb.

Heterozygous - When the genotype is made up of different (hetero = different, zygous= pair) alleles. Bb.

Incomplete dominance - When there is no dominance or recessiveness instead different alleles are expressed in a phenotype that is a blend of the two. Certain flowers and animal coats show incomplete dominance. Red and white alleles are expressed as pink.

Codominance- if both alleles are expressed. See pg. 360 blood types are both codominant

and an example of multiple alleles

Genome - all the genes of an organism. They have sequenced the human genome. This is called the Human Genome Project.

Of the estimated 20,000-25,000 genes in the human genome, close to 2,400 are

known to show Mendelian inheritance of dominance / recessive . Another 2,000 are

suspected to behave in this manner. The remainder behave in an unknown fashion.