Chromosomal and molecular basis of inheritance study guide

Study guide for quiz #9...I'm sick and tired of these quizzes, okay??!?!! There's no way that we've only taken 9 quizzes...anyway if I don’t pass this quiz with flying colors I’m going to lose my marbles

Linked Genes

Linked Genes

Genes that are located on the same chromosome, they do not assort independently, tend to be inherited together, and crossing over accounts for recombination of linked genes

Unlinked Genes

Genes located on separate chromosomes. Independent assortment account for the recombination

Sex linked genetic traits

They are carried only on the x-chromosome, they carry most genes related to sex, but they also carry genes unrelated to sex

Chromosomal Theory of Inheritance

The theory that the behavior and movement of an organism’s chromosomes, during meiosis, accounts for Mendel’s two laws

Autosomal Chromosomes(Autosomes)

Chromosomes derived from somatic(normal body) cells; most of an organisms chromosomes are autosomal. (ex. in humans 22/23 of our homologous pairs are autosomal)

Sex Chromosomes

Chromosomes derived from germ(special reproductive) cells only a few of an organism’s chromosomes are sex chromosomes. (ex. humans only have one homologous pair (X and Y))

Sex-Linked Genes

Genes that are located specifically on the sex chromosomes(i.e., the X or Y chromosome)

Recombinants

Offspring possessing new combinations of traits that are inherited from both parents. These are phenotypically distinct from their parents because they have traits that are a combination of those possessed by both parents.

Gene mapping

A technique that allows geneticists to use recombination and crossing over data in order to determine a gene’s exact position on a Chromosome; the technique determines that loci of genes

X-linked genes

Sex-linked genes that are located exclusively on the X-chromosome(there is no counterpart on the Y)

Barr bodies

A condensed, inactive X-chromosome in the nucleus of cells of mammalian(mammal females)

Nondisjunction

A chromosomal error that can occur during meiosis 1 or 2. The members of a homologous pair of chromosomes or sister chromatids fail to separate

Aneuploidy

The condition of an offspring having an abnormal number of chromosomes due to an abnormal gamete fertilizing a normal gamete

Trisomy

Type of aneuploidy in which the organism has an extra copy of one particular chromosome. This condition is often expressed as 2n+1

Monosomy

Type of aneuploidy in which the organism has only a single copy of one particular chromosome. This condition is often expressed as 2n-1

Capital letter

normal allele

DNA is made up of

monomers called nucleotides

What are the names of the nucleotides that make up DNA?

The phosphaste group, 5-C sugar(deoxyribose), one of four nitrogenous bases(A, T, C, or G)

Pyrimidines

C and T

Purines

A and G

A purine always bonds to a

pyrimidine

Genes are

Functional portions of DNA that code for proteins

DNA possessed the unique ability to

self-replicate

Replication is a

semi-conservative process

Chargaffs Rule

The base pairing rule in DNA. A always bonds with T. C always bonds with G

Double helix

Normal state of the DNA molecule; two strands of nucleotides coiled around each other in a very specific pattern

Base pairing

Bonding between two nitrogenous bases; once the two bases are bonded together, we call it a “Base Pair”

Complimentary

Refers to each strand in a DNA molecule containing only bases that are the complements (opposites) of those on the other strand

Ian

Shane

Antiparallel

Refers to the fact that two strands in any DNA double helix run in opposite directions to one another.

Helicase

The enzyme that initiates replication by unwinding the double helix at many specific locations along it’s length

Origins of replication

Special sites within the DNA molecule where replication begins; when these sites are unwound by helicase, they form replication bubbles

Replication forks

A Y-shaped region at each end of replication bubble where new strands are forming and elongating

Gyrase

Enzyme that prevents the accumulation of twists and relieves tension in the DNA molecule after it is unwound

Single strand binding protein

A protein responsible for actually holding the DNA strands apart during replication

DNA polymerase

The enzyme responsible for the actual synthesis and elongation of the new, complementary stands. It attaches free nucleotides to those found on the parent stand and is the major replication enzyme

Elongation

Process in which DNA polymerase moves down each parental strand and attaches complementary nucleotides(one at a time) to each base present in the parent strand

Mismatch repair

DNA repair mechanism that fixes mistakes that are made when the DNA is actually being replicated. It involved DNA polymerase actually proofreading the strand and fixing any errors it finds along the way

Excision repair

DNA repair mechanism that involves the repair of physical and/or chemical damage that occurs to existing, completed strands of DNA that are not currently replicating

Mutations

Changes to the genetic information; many agents can cause mutations, and more mutations have adverse effects

Nucleases

DNA repair enzymes that carry out excision repair; they located a mutated segment of DNA and then cut out the damaged section; the other nucleases will then replace this gap with correctly paired nucleotides

An error in chromosomal inheritance

One gamete receives two of the same chromosome, other receives no copy

Polyploidy

An organism possesses more than two complete sets of chromosomes

Mosaicism

Chromosomal differences that do not show up in every cell

Helicase, Gyrase, DNA polymerase

are all enzymes

Lower case letter

‘Defected allele’