Bio 2230: Chapter 1
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scientific study of heredity
why is genetics central to biology?
because gene activity underlies all life processes
what is classical genetics?
use of crosses to breed new strains of organisms and to understand how traits are transmitted.
Genetics is often divided into _________ and _________ genetics
what is an important tool used in classical genetics?
isolation of mutants affecting particular traits which can then be compared to normal strains
what is modern genetics?
study of genes at the molecular level
how was the first genetic maps of genes on chromosomes generated?
how is modern genetics made possible?
made possible because of advances in cloning and sequencing genes
Modern genetics has provided an enormous understanding of about: (4)
- physical nature of genes
- their expression patterns
- role in development and disease
- how their products react
what is genomics?
branch of genetics that studies organisms in terms of their genomes
How are many genes first identified?
through their effect on phenotype, and then later cloned and sequenced
which organisms have DNA as their genetic material?
with the exception of some RNA viruses, genetic material of all viruses, prokaryotes and eukaryotes
full DNA sequence of an organism
how is genetic information convey in DNA?
conveyed in the sequence of nucleotides
what is a gene? what do they encode?
- segment of DNA bearing a specific sequence of nucleotides
- encode traits that are passed from parent to offspring
describe the chromosome of a prokaryote and a eukaryote.
- prokaryote: singular circular chromosome
- eukaryote: many linear chromosomes within a nucleus
describe the structure of the chromosome.
single molecule of DNA wrapped around histone proteins
what is the function of histones?
- allow efficient packing of the genome
- involved in gene regulation
where do eukaryotes contain extranulear DNA? (2)
The laws of inheritance was first created by?
From his experiment with crosses between pea plants, Gregor Mendel concluded what 2 things?
- inherited characteristics are determined by genes
- each organism contains 2 copies of each gene ( one from father, one from mother)
what are alleles? (2)
- alternative versions of genes
- account for variations in inherited characteristics
organisms having a pair of identical alleles for a trait
organisms having 2 different alleles for a gene
observable characteristics of an organism
genetic makeup of an organism
The ________ interacts with the environment (internal and external) to produce the _________.
What was Mendel's first Law? what was another name for it?
- members of a gene pair segregate randomly into gametes
- principle of segregation
What was Mendel's Second Law?
- different genes assort independently during gamete formation (only applies to genes on different chromosomes or genes that are located very far apart on the same chromosome)
- principle of independent assortment
what is gene expression?
process by which a gene produces its product and that product carries out its function
what is the one-gene-one-polypeptide hypothesis?
genes provide instructions for making proteins (not all proteins are enzymes)
what is transcription?
process by which a segment of DNA (a gene) is copied into RNA
DNA is locally unwound and ______________ uses one strand as a template to synthesise an RNA copy.
ribosomal RNA: used to make ribosomes (translation machines of the cell)
transfer RNA: decode DNA language into protein language by bringing amino acids to ribosomes
messenger RNA: specify the amino acid sequences of proteins
define translation. where does is occur?
- process by which the base sequence of mRNA is converted into an amino acid sequenceoccurs in ribosomes
what is genetic code?
base sequence information that specifies the amino acid sequence of a protein
what is a codon?
three-nucleotide sequence of mRNA that specifies an amino acid
what is a switch regarding the operon model?
a switch is made up of a protein (transcription factor) whose conformation can be altered by ligand binding and a DNA sequence to which it binds (promoter)
Genetic differences arise through the process of what 3 things?
what is mutation?
change in genetic material (substitutions, deletions, insertions, translocations, etc.)
what is recombination?
exchange of chromosomal material between homologous chromosomes at meiosis
what is selection?
over long periods of time, this process leads to a change in frequencies of genes affecting certain traits
All genetic variation ultimately is derived from ________.
Describe the hypothetico-deductive method of investigation.
- involves making observations about the natural world
- generating hypothesis to explain observations
- hypothesis must generate experimental predictions
- which can be tested under controlled conditions
name the 4 subdisciplines of genetics.
- transmission (classical) genetics
- molecular genetics
- population genetics
- quantitative genetics
what does transmission (classical) genetics deal with? (2)
- deals with how genes and genetic traits are inherited
- how genes recombine (genetic crosses)
what does molecular genetics deal with?
deals with molecular structure and function of genes (gene expression)
what does population genetics deal with ?
deals with heredity in groups of individuals for traits that are determined by one or only a few genes
what is quantitative genetics?
- deals with heredity in groups but the complex traits encoded by many genes simultaneously
- statistics and genetics
what is the goal of basic research?
- goal of understanding fundamental phenomena
- used to fuel more basic research
what is the goal of applied research?
goal of overcoming specific problems in society or exploiting discoveries derived from basic research
what does a genetic map do?
shows the relative locations of genes along a chromosome as well as the distance between genes
what understanding does genetic maps give us?
understanding of the organization of genes along chromosomes
what are the qualities that make an organisms a good model for genetic experimentation? (5)
- well known genetic history
- short life cycle
- mating produces large amount of offspring
- easy to handle (genetically traceable)
- genetic variation between individuals in a population
what is applied genetics?
genetic screens for metabolic diseases
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