1. Genetics Refresher Guide

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

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

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

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

6. 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

9. 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

11. 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.

12. 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

16. 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

19. 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.

20. Chromosomal Mutations
Gene Mutations

21. 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

23. 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.

24. 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.

25. 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

28. 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

29. 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