Unit 6 - Inheritance of Traits Study Guide

These flashcards cover key terms and concepts related to the inheritance of traits and genetics.

What is Meiosis?

the specialized process of cell division that reduces the chromosome number by half, resulting in the production of gametes (sperm and eggs). It involves two sequential rounds of division, meiosis I and meiosis II, and is crucial for sexual reproduction as it ensures genetic variation through mechanisms like crossing over and random assortment of chromosomes.

What is Crossing Over?

a genetic exchange that occurs during prophase I of meiosis, where homologous chromosomes swap segments of genetic material. This process creates new combinations of alleles in gametes, significantly contributing to genetic diversity among offspring.

What defines a Diploid Cell?

a type of cell that contains two complete sets of chromosomes, one set inherited from each parent. In humans, this means there are 46 chromosomes in total (23 pairs). Diploid cells make up the majority of an organism’s body cells, including skin, blood, and muscle cells.

What are Gametes?

reproductive cells produced through meiosis that are necessary for sexual reproduction. In humans, males produce sperm and females produce eggs, both of which are haploid, containing only one set of chromosomes (23). During fertilization, gametes combine to form a diploid zygote.

What is a Haploid Cell?

a cell that contains only one set of chromosomes, which is half the number found in diploid cells. In humans, haploid cells are the gametes (sperm and eggs), containing 23 chromosomes. This halving of chromosome number is crucial for maintaining genetic stability across generations.

What are Homologous Chromosomes?

pairs of chromosomes that have the same structure and gene sequence but may carry different alleles, which are variants of a gene. Each pair consists of one chromosome from each parent and plays an essential role in genetic diversity through meiosis.

What is a Somatic Cell?

any body cell that is not a germ cell (gamete). Somatic cells are diploid in humans, meaning they contain two sets of chromosomes (46 total). These cells make up the tissues and organs of an organism, contributing to its overall structure and function.

Who is Gregor Mendel?

an Austrian monk and scientist known as the 'Father of Genetics' for his pioneering work in understanding heredity. He conducted experiments with pea plants, leading to the discovery of fundamental genetic principles such as segregation, independent assortment, and the concept of dominance.

What is the Principle of Dominance?

a genetic theory posited by Mendel which states that in heterozygous genotypes, the dominant allele masks the recessive allele, determining the organism's phenotype. This means that the presence of a dominant allele will be expressed in the organism, overshadowing the effects of the recessive allele.

What does the Principle of Segregation state?

states that during the formation of gametes, the two alleles for a trait separate from each other so that each gamete carries only one allele for each gene. This principle explains how traits are inherited independently of one another.

What is Phenotype?

the observable physical or biochemical traits of an individual, which result from the interaction of its genotype with the environment. Examples of phenotypes include physical attributes such as height, eye color, and blood type.

What is Genotype?

the genetic makeup of an individual, represented by the specific alleles present at a given gene locus. It can influence an organism's phenotype, but two individuals may share the same phenotype while having different genotypes.

What is a Punnett Square?

a diagram used in genetics to predict the possible genetic outcomes of a cross between two individuals. It helps visualize how alleles from each parent combine, allowing predictions about the ratios of genotypes and phenotypes among offspring.

What is a Karyotype?

a visual representation or photographic display of an individual’s complete set of chromosomes, organized by size and shape. Karyotyping is used to identify chromosomal abnormalities, such as aneuploidies (e.g., Down syndrome) and structural defects.

What are Autosomes?

chromosomes that do not determine the sex of an individual. Humans have 22 pairs of autosomes (totaling 44) alongside one pair of sex chromosomes (XX or XY), and they carry the genes responsible for most bodily functions.

What are Sex Chromosomes?

chromosomes that determine the biological sex of an individual. In humans, there are two types: X and Y. Females typically have two X chromosomes (XX), while males have one X and one Y chromosome (XY), determining their phenotypic sex.

What is the Central Dogma of Molecular Biology?

the framework that describes the flow of genetic information in biological systems, stating that DNA is first transcribed into RNA, which is then translated into proteins. This process is fundamental to all living organisms.

What is the role of RNA Polymerase?

essential enzyme that synthesizes RNA from a DNA template during the transcription process. It is responsible for unwinding the DNA and assembling a complementary RNA strand, producing messenger RNA (mRNA) for translation.

What is mRNA?

a type of RNA that carries genetic information from DNA in the nucleus to ribosomes in the cytoplasm, where proteins are synthesized. mRNA serves as a template that is translated into a specific amino acid sequence during protein synthesis.

What is tRNA?

a type of RNA that transports specific amino acids to the ribosome during the translation phase of protein synthesis. Each tRNA has an anticodon that is complementary to a codon in the mRNA, ensuring that the correct amino acid is incorporated into the growing polypeptide chain.

What is rRNA?

a critical component of ribosomes, where protein synthesis occurs. It helps form the structural and functional core of the ribosome and plays key roles in catalyzing the biochemical reactions that link amino acids together to form proteins.

What is an Amino Acid?

the organic compounds that serve as the building blocks of proteins. Each amino acid consists of an amino group, a carboxylic acid group, and a unique side chain. There are 20 standard amino acids, and their sequence determines the structure and function of proteins.

What are Codons?

sequences of three nucleotides in mRNA that specify a particular amino acid or signal the termination of protein synthesis. Each codon corresponds to a specific amino acid, determining the polypeptide chain's composition during translation.

What is a Start Codon?

a specific codon (AUG) in the mRNA that signals the beginning of protein synthesis. It codes for methionine, which is always the first amino acid added to a growing polypeptide chain during translation.

What are Multiple Alleles?

a situation in genetics where a single gene exists in more than two forms (alleles) within a given population. This leads to a variety of phenotypes and can influence traits such as blood type, where three alleles (IA, IB, and i) exist for the gene determining ABO blood groups.

What is Codominance?

a pattern of inheritance where both alleles contribute equally and visibly to the phenotype of an organism, resulting in a phenotype that showcases both traits simultaneously. An example is seen in AB blood type, where both A and B alleles are expressed.