Genetics Refresher Guide

What does genetics mean? Deals with heredity and variation Involves cells, individuals, offspring, populations

What is the center of heredity in a cell? Nucleus In bacterial cellnucleoid region

What is the genetic material? DNAdeoxyribonucleic acid RNAribonucleic acid In viruses, DNA or RNA can be utilized Measles Avian Flu

How is DNA organized to serve as genetic material? Usually organized as a double helix although sometimes single stranded in viruses.

What is a gene? Functional unit of heredity More specifically a linear (line) array of nucleotides Nucleotides are the chemical building blocks (monomers) of DNA and RNA Storage unit that can undergo replication, mutation, and expression

What is a chromosome? Usually a circular DNA molecule organized into genes in viruses and bacteria In eukaryotes (contains a nucleus) the chromosome is composed of linear DNA molecule associated with proteins

When and how can a c-some be visualized? In eukaryotes-during mitosis or meiosis (specifically during prophase) In prokaryotes, it can be seen if the DNA is released from the viral head.

How many c-somes does an organism have? Most species contain a specific number of c-somes are diploid (2n) with c-somes found in pairs (homologous) Homologs are identical in length and location of the centromere Centromere is the point of spindle fiber attachment during division. Chromosome count

What is accomplished during the process of mitosis and meiosis? Mitosis-process by which genetic material of eukaryotic cells is duplicated and distributed during cell division Meiosis- the process where cell division produces gametes in animals and spores in most plants Gametes=haploid

What are the sources of genetic variation? Chromosomal mutations Includes duplication, deletion or rearrangement of c-some segments Gene mutations Causes changes genotype Includes changes such as substitution, duplication, or deletion of nucleotides Alternate forms of a gene caused from mutation is called an allele.

Chromosomal Mutations Gene Mutations

How does DNA store genetic info? They are in the form of a genetic code (A, T, G, C) The code specifies the chemical composition (amino acid composition) of the proteins

How is the genetic code organized? triplet, or codon Each nucleotide has three parts: a sugar molecule, a phosphate molecule, and a structure called a nitrogenous base. The nitrogenous base is the part of the nucleotide that carries genetic information, so the words "nucleotide" and "base" are often used interchangeably. The bases found in DNA come in four varieties: adenine, cytosine, guanine, and thymine often abbreviated as A, C, G, and T, the letters of the genetic alphabet.

How is the genetic code expressed? The coded info in DNA is first transferred by transcription into messenger RNA After the mRNA associated with the ribosome, it is then translated into a protein molecule.

Are there exceptions where proteins are not the end product of a gene? Yes! Ribosomal RNA-part of ribosome Transfer RNA-involved in translation but is transcribed and not translated

Many serve as enzymes! Which help to control cellular metabolism Why are proteins so important to living organisms that they serve as the end product of the vast majority of genes? Many serve as enzymes! Which help to control cellular metabolism

Why are enzymes necessary to living organisms? Enzymes lower activation energy for biochemical reactionshelp to speed them up. Otherwise they would proceed too slowly