Genetics multiple choice

Questions and Answers

What happens to a protein after it has been synthesized?

It converts into a different substance.

It folds into its active shape for function. (correct)

It remains in the ribosome.

It is destroyed immediately.

What is a dominant allele?

An allele that is weaker than a recessive allele.

An allele that is only expressed in the absence of a dominant allele.

An allele that can never be inherited.

An allele that is always expressed if present. (correct)

What does the Law of Segregation state?

Each characteristic is determined by multiple genes.

Each gamete receives only one allele from each gene pair. (correct)

Genotype does not affect phenotype.

Each gamete receives both alleles from a pair.

Who is known as the father of modern genetics?

Gregor Mendel Signup and view all the answers

What is the relationship between genotype and phenotype?

Phenotype is the observable characteristic influenced by genotype and environment. Signup and view all the answers

How did Mendel's approach to genetics differ from that of his contemporaries?

He used statistical analysis in his experiments. Signup and view all the answers

What occurs to proteins that are not used in the cell immediately after synthesis?

They are packaged for release to perform functions elsewhere. Signup and view all the answers

What did Mendel’s experiments with peas reveal about traits?

Traits are controlled by pairs of factors, or genes, inherited from each parent. Signup and view all the answers

What defines a recessive allele in genetics?

It is expressed only in the absence of a dominant allele. Signup and view all the answers

Study Notes

Phenotype Ratios

F2 phenotype ratio is 9:3:3:1, representing dominant and recessive traits.
Dominant traits: 9 show both dominant features, 3 show one dominant and one recessive, 1 shows both recessive features.

Linkage of Genes

Linked genes are situated on the same chromosome and inherited together.
Independent assortment occurs when genes are on separate chromosomes.
Example with fruit flies: long wings (dominant) and wide abdomen (dominant) crossed with vestigial wings (recessive) and narrow abdomen (recessive) shows that linked genes do not assort independently.
Crossing over during meiosis can lead to non-parental phenotypes.

F2 Crosses of Fruit Flies

F1 individuals exhibit long wings and wide abdomens from parental crosses.
F2 offspring yield a ratio of 3 long wings and wide abdomens to 1 vestigial wings and narrow abdomens.

Sex Linkage

Genes on X or Y chromosomes are sex-linked, with X being more substantial for genetic characteristics.
Sex-linked genes influence traits differently between males and females due to chromosome composition.

Genetic Engineering Techniques

Involves using plasmids as cloning vectors; the insulin gene is inserted into bacteria.
Ligation: DNA ligase joins foreign DNA with plasmid.
Transformation: Recombinant DNA is introduced into bacteria.
Expression: Bacteria multiply, cloning genetically identical cells.

Applications of Genetic Engineering

Plants: Herbicide-resistant crops created by integrating bacterial genes.
Animals: Sheep engineered to produce proteins for medical treatments in their milk.
Microorganisms: Bacteria produce human insulin to avoid allergic reactions to animal insulin.

Genetic Principles

Gregor Mendel, founder of modern genetics, studied pea plants and established key genetic principles.
Concepts include dominance (stronger trait expressed), recessiveness (trait masked), and gene alleles (options for a characteristic).

Law of Segregation

Each characteristic governed by a gene pair, which segregate during gamete formation.
Each gamete receives one factor from each pair.
Phenotype: Observable traits influenced by genotype and environment.
Genotype: Genetic composition of an organism.

Transcription Process

Enzyme DNA helicase unwinds DNA, enabling mRNA synthesis.
mRNA utilizes uracil instead of thymine.

Movement of mRNA

mRNA exits the nucleus into the cytoplasm via nuclear pores.
Ribosomes formed from rRNA and proteins synthesize proteins using mRNA.

Transfer RNA (tRNA)

tRNA carries specific amino acids to ribosomes based on anticodon-codon recognition.
Anticodons on tRNA are complementary to mRNA codons, guiding amino acid sequence assembly.

Translation Process

Ribosome assembles proteins by matching mRNA codons with tRNA anticodons.
Amino acids are linked by peptide bonds.
Completion of protein synthesis occurs when ribosome encounters a stop codon.

Protein Distribution

Proteins are used within the cell or packaged for external functions.

Description

Test your knowledge on Mendelian genetics with this quiz focusing on phenotype ratios in F2 generations. Understand the concepts of dominant and recessive traits, and explore the implications of gene linkage versus independent assortment. Perfect for students studying genetics!