Chapter 1 Intro to Genetics

The study of heredity, how inherited variation is encoded, replicated, and expressed, and how it evolves over time.

Genetics

What are the major subdivisions of genetics?

• transmission

• molecular

• population

The complete set of genetic instructions for any organism

Genome

Describe the 2 step process of evolution

1. Inherited differences arise randomly

2. The proportion of individuals with particular differences increases or decreases.

True or False: Research findings on one organism’s gene function can often be applied to other organisms?

True

because all organisms have similar genetic systems meaning that the study of one organism’s genes reveals principles that apply to other organisms

All life forms are genetically related?

True

because the process by which genetic information is copied, decoded, and instructed in the same format that is remarkably similar for all forms of life

The genes from one organism can often function in another organism?

True

because all organisms have similar genetic systems, genes can often function in foreign cells (ex: e.coli used to make insulin using the insulin gene extracted from humans)

• encompasses the basic principles of heredity and how traits are passed from one generation to the next

• think of punnet squares, traits inherited, etc.

• how an individual inherits its genetic makeup and how it passes its genes to the next generation.

Transmission Genetics

• studying the gene itself, how it transcribes, translates, mutates, gene regulation, etc.

• concerns the chemical nature of the gene itself: how genetic information is encoded, replicated, and expressed

• the main focus is is the gene and its structure, organization, and function.

Molecular Genetics

• basically the study of evolution

• explores the genetic composition of populations and how that composition changes geographically and over time.

• focus is the group of genes found in that population

Population Genetics

What are the 6 model genetic organisms used?

• fruit fly

• mouse

• bacteria (ex: e.coli)

• Nematode

• Yeast

• Thale-cress plant

zebrafish (used in studying skin pigmentation) is mentioned also

What makes a good genetic model organism?

• short generation time

• large manageable numbers of progeny (litters)

• adaptability to the lab environment

• inexpensive

Theory that genetic information travels from different parts of the body to reproductive organs

• Pangenesis

• this was INCORRECT (refer to rat tail experiment)

Theory that genes blend and mix

• Blending inheritance

• this was INCORRECT (red and yellow don’t make a orange baby)

Theory that a miniature organism (homunculus) resides in sex cells and that all traits are inherited from one parent

• Preformationism

• this was INCORRECT because there is no miniature baby but rather forms through mitosis/meiosis

Theory that acquired traits over a life span become incorporated into hereditary information/past onto offspring

• Inheritance of acquired characteristics

• this is INCORRECT (ex: building muscle does not mean your offspring will be born with muscles also)

all life is composed of cells, cells arise only from preexisting cells, and the cell is the fundamental unit of structure and function in living organisms

Cell Theory

Theory that the cells in the reproductive organs carry a complete set of genetic information that is passed to the egg and sperm

• Germ-plasm theory

• this is CORRECT and opposes Pangenesis in that there is no traveling from a body part to the reproductive organs but rather it is already IN the reproductive organs already

Traits are inherited in accord with defined principles (genes and alleles)

• Mendelian inheritance

• this is CORRECT

cells that lack a nuclear membrane and do not generally possess membrane-bounded organelles

Prokaryotic Cells

complex cells possessing a nucleus and membrane-bounded organelles such as chloroplasts and mitochondria.

Eukaryotic Cells

The unit of information that encodes a genetic characteristic

Gene

Genes come in multiple forms/variations called _______

Alleles

ex: a gene for hair can have alleles for brown hair and black hair (genotype) but the phenotype itself is the dominant allele out of the alleles in the genotype

Nitrogenous bases for DNA?

• Adenine

• Guanine

• Thymine

• Cytosine

Nitrogenous bases for RNA?

• Adenine

• Guanine

• Uracil

• Cytosine

Explain the makeup of chromosomes and how genes are located on them.

• DNA contains sequences of ATCG that encode for a specific gene in which that gene provides instructions to make proteins that are for a characteristic or a specific role in the body

• These DNA sequences tightly wrap around ball shaped proteins making histone structures and eventually chromatin with multiple histones together

• These chromatins tightly pack and form what is a chromosome

• note that each chromosome has a large number of genes

Separation of chromosomes in the division of somatic (nonsex) cells.

Mitosis

Pairing and separation of chromosomes in the division of sex cells to produce gametes (reproductive cells)

Meiosis

Genetic information is transferred from ____ to ____ to ____

• DNA

  • transcription occurs

• RNA

  • Translation occurs into amino acid sequence

• Protein

______ mutations affect the genetic information of a single gene

Gene

____ mutations alter the number or the structure of chromosomes and therefore usually affect many genes.

Chromosome

True or False: Many traits are affected by multiple genes that interact in complex ways with one another and with environmental factors.

True

ex: height is determined by many genes and environmental factors such as nutrition

True or False: Evolution requires genetic change in populations

True

Father of genetics and discovered laws of inheritance (dominant and recessive traits)

Gregor Mendel

Developed Cell Thoery

Schlieden and Schwann

Created the germ-plasm theory and disproved Inheritance of Acquired Traits

Weismann

Invented Polymerase chain reaction (PCR) that allowed amplification of tiny amounts of DNA quickly

Kary Mullis

Invented CRISPR-Cas9 gene editing technology to treat genetic diseases, improve crops, etc.

Jennifer Doudna and Emmanuelle Charpentier

Can a phenotype tell you what a person’s genotype is?

No because a phenotype only tells the dominant alleles present that you can see with your eyes. You don’t know if that individual is carrying recessive alleles.