01 basic genetics and biochemistry

chromosome

• Consists of a long DNA molecule that is foldedaround proteins

• each unit consists of two rodlike structures joined together at a constricted point.

chromatin

DNA and chromosome proteins

centromere

the region of the chromosome where chromatids are held together

karyotype

• An arrangement that provides a picture of the complete set of chromosomes

• It shows the diferences in size and banding pattern of the chromosomes.

• useful in determining the chromosome number of a species.

loci

the position or location on a chromosome where a particular gene is found.

alleles

diferent forms of the gene that can be found on the same loci.

mitosis

Increase in the number of cells from a single-celled zygote that contains the exact same set of chromosomes as the original single-celled zygote

meiosis

• Produces four haploid cells after the process, each with own genetic composition which is diferent from mother cell

• Haploid reproduction cells (gametes, spores) are the product of this division.

y chromosome

• contains the SRY gene (sex determining region of the Y chromosome) located on the short arm of the Y chromosome.

• Its presence provides the initial signal for diferentiation of the gonads in the embryo to develop into a testis rather than an ovary.

chromosomal abberations

These are variations in the number of individual chromosomes as well as rearrangements of the genetic material either within or among the chromosome.

trisomy

with extra chromosome

monosomy

lacks one chromosome

euploidy

contains a complete diploid set of chromosomes.

aneuploidy

occurs when an organism loses or gains one or more chromosomes.

DNA

• deoxyribonucleic acid

• Consists of two strands that wrap around each other to resemble a twisted ladder

• consists of four diferent bases:

  • Purines: Adenine, Guanine

  • Pyrimidines: Thymine, Cytosine

• DNA strands in a double helix MUST havematching base pairs

nucleotides

linear arrangement of repeating similar units

structural gene

A segment of DNA including all the nucleotides that are transcribed into mRNA

codons

DNA bases

replication

begins with separation of the double helix. As the strands unwind, nucleotides inthe cell pair up with the complementary bases.

DNA polymerase

enzyme that catalyzes replication

transcription

• the DNA sequence in one of the strands acts as a template for synthesis of RNA

• synthesis of new proteins begin here

RNA polymerase

enzyme that catalyzes transcription

mRNA, rRNA, or tRNA

produced when DNA is transcribed to RNA

RNA

further transported outside the nucleus to the cytoplasm where it becomes active in translation

messenger

m in mRNA

transfer

t in tRNA

ribosomal

r in rRNA