Chapter 3: Principles of Genetics

Who formed the foundational work on genetics?

Gregor Mendel

What did Mendel’s experiment show?

Traits are passed down through discrete, or particulate, units rather than blending.

What did Mendel’s P1 generation show?

A single, dominant trait and none of the recessive trait

What happened when Mendel crossed yellow and green peas?

All the offspring in the first generation had yellow peas

What is Mendel’s Law of Segregation?

During gamete formation, the two alleles for each gene separate from each other, so each gamete ends up with only one allele

What is a punnett square?

A diagram that predicts the possible genetic outcomes, or genotypes and phenotypes, of an offspring from two parents

How are punnett squares used in biotechnology?

Used to predict the probability of offspring inheriting specific traits

What is the Law of Independent Assortment?

A principle of genetics stating that alleles for different traits segregate independently from each other during the formation of gametes

Why is the Law of Independent Assortment important in biotechnology?

Fundamental to creating genetic variation

What is a testcross?

A genetic cross between an individual with an unknown genotype and a homozygous recessive individual to determine the genotype of the unknown parent

What is homozygous

Two same alleles

What is heterozygous

Two different alleles

Why are testcrosses important in biotechnology

Determine the genotype of an individual with a dominant trait, which is crucial for genetic research, breeding, and understanding disease inheritance

What is incomplete dominance

A genetic trait where neither allele is fully dominant, resulting in a blended, intermediate phenotype in a heterozygous individual

What does incomplete dominance show in biotechnology?

How intermediate phenotypes can be created through blending of two parental traits

What is codominance

A genetic inheritance pattern where two different alleles for a trait are both fully and separately expressed in the offspring's phenotype

What is an example of a trait determined by codominance

Blood ex. Type AB

What is a polygenic inheritance

A pattern of inheritance where a single trait is controlled by multiple genes, rather than just one

Why is codominance important in biotechnology?

It allows for the simultaneous expression of multiple alleles

What is a classical example of polygenic inheritance

Human Height

What type of results does polygenic inheritance produce

A continuous range of phenotypes, or a continuous spectrum, rather than distinct categories

How is sex determined

Primarily based on the presence or absence of the Y chromosome. 

Why is sex determination important in biotechnology

Optimizing crop yields, improving animal breeding, advancing medical treatments, and studying evolution

how are sex linked traits determined

These genes carried on the sex chromosomes

why are males more likely to express x-linked disorders

because they only have one x chromosome

how do females express sex linked disorders

they typically do not express sex linked disorders

why is it important to understand sex-linked inheritance in biotechnology

By predicting the inheritance of genetic conditions, developing diagnostic tools, and informing the creation of targeted therapies and genetic counseling strategies

what are chromosomal alterations

genetic changes that occur when there is a problem with the number or structure of chromosomes

what is deletion

type of mutation where a segment of a chromosome or a piece of DNA is lost

what is inversion

type of mutation where a segment of a chromosome reorients in a different location

what is translocation

the movement of materials from one part of an organism to another, or the exchange of genetic material between chromosomes

what is duplication

a genetic mutation where a segment of DNA or a chromosome is copied, leading to extra copies of that region

what is crossing over

the exchange of genetic material between homologous chromosomes that occurs during meiosis

why is crossing over important in science and biotechnology

creates gametes that contain new combinations of genes,

when does crossing over occur

during prophase I of meiosis

what is nondisjunction

the error in cell division where homologous chromosomes or sister chromatids fail to separate correctly, leading to gametes (sex cells) or daughter cells with an abnormal number of chromosomes

what is the result of nondisjunction

gametes with an abnormal number of chromosomes, leading to offspring with conditions like trisomy (an extra chromosome, as in Down syndrome) or monosomy (a missing chromosome, as in Turner syndrome)

what diseases does nondisjunction explain

down syndrome, turner syndrome, and klinfelter syndrome

what is down’s syndrome

person has 47 chromosomes instead of the usual 46 because of an extra copy of chromosome 21

what is turner syndrome

a genetic disorder that affects females, typically caused by the absence or partial deletion of one X chromosome

what is klinefelter syndrome

a genetic disorder that affects males, caused by an extra X chromosome