Heredity, Genes and Alleles

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Questions and Answers

Explain how the processes of meiosis and mitosis contribute differently to genetic diversity in sexually reproducing organisms.

Meiosis increases genetic diversity through processes like crossing over and independent assortment, creating unique combinations of alleles in gametes. Mitosis, on the other hand, produces identical daughter cells, maintaining genetic consistency within an organism.

Distinguish between the terms 'phenotype' and 'genotype,' and provide an example to illustrate how different genotypes can result in the same phenotype.

Genotype refers to the genetic makeup (alleles) of an organism, while phenotype is the observable expression of those genes (physical traits). For example, both a homozygous dominant (AA) and a heterozygous (Aa) genotype can result in the same dominant phenotype.

Describe a scenario where selective breeding might be used and a scenario where genetic engineering might be used. What are the key differences between these processes?

Selective breeding could be used in agriculture to develop plants with higher yields by repeatedly breeding those with the most desirable traits over multiple generations. Genetic engineering techniques can be used in medicine to introduce specific genes into cells to correct genetic defects. Selective breeding relies on natural genetic variation within a species whereas genetic engineering introduces new genes to the organism.

Explain how a pedigree chart can be used to determine whether a particular trait is dominant or recessive.

<p>If a trait is dominant, affected individuals will appear in every generation of the pedigree. If a trait is recessive, it may skip generations, and affected individuals typically have unaffected parents who are carriers.</p> Signup and view all the answers

In a species of flower, red (R) and white (W) are codominant. Heterozygous individuals (RW) display both red and white coloration. If two heterozygous flowers are crossed, what are the possible genotypes and phenotypes of their offspring?

<p>The possible genotypes are RR, RW, and WW. The phenotypes would be red flowers (RR), flowers with both red and white coloration (RW), and white flowers (WW).</p> Signup and view all the answers

Flashcards

Heredity

Traits passed from parent to offspring.

DNA

Instructional code inside the nucleus directing cell activities.

Genes

The factor controlling a specific trait.

Meiosis

Cell division producing sperm or egg cells for reproduction.

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Phenotype

The expressed physical appearance of a trait.

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Study Notes

Heredity is the traits that are passed on from parent to offspring
The nucleus contains DNA and the nuclear membrane, controlling all cell activities
DNA is the instructional code located in the nucleus dictating actions of the cells include
Genes are the factors that controls a trait you exhibit
Alleles represent the different forms of a gene
Meiosis produces 4 sex cells (sperm or egg) used to pass traits to offspring
Mitosis is cell reproduction when one body cell becomes 2

Dominant & Recessive Traits

A dominant trait overshadows other traits and is expressed
A recessive trait hides in the background and can only be expressed in homozygous form

Genotype & Phenotype

Genotype is the combination of alleles represented by letters
Phenotype is the physical appearance of a trait

Allele Combinations

Heterozygous/Hybrid means two different alleles/letters for one trait (Dd)
Homozygous/Purebred means two of the same alleles/letters for one trait

Methods of Genetic Manipulation & Selection

Genetic engineering alters DNA to get desired traits
Selective breeding selects organisms with desired traits to breed and pass on traits
Gene therapy adds or deletes genes to correct or rid disorders

Breeding & Reproduction

Hybridization crosses 2 organisms resulting in an organism with desired traits
Cloning makes a new organism with the same genes from which it was produced
Inbreeding is when two organisms with the same characteristics mate

Pedigree & Codominance

A pedigree is a way of tracing a trait through a family tree
Codominance is when dominant and recessive traits are combined in heterozygotes such that both traits are expressed at the same time

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Description

The lesson covers heredity: traits passed from parent to offspring. Key topics include the roles of the nucleus, DNA, genes, and alleles, along with meiosis and mitosis. It also differentiates between dominant and recessive traits, genotype and phenotype, and heterozygous and homozygous allele combinations.