Biology Chapter on DNA and Reproduction

DNA is the blueprint of life, holding genetic information that determines an organism's traits.

DNA's structure resembles a twisted ladder, composed of sugar, phosphate, and nitrogenous bases.

DNA's bases pair specifically: Adenine (A) with Thymine (T), and Guanine (G) with Cytosine (C).

RNA is a single-stranded molecule that plays a crucial role in protein synthesis, using uracil (U) instead of thymine (T).

There are three types of RNA: mRNA (messenger RNA), rRNA (ribosomal RNA), and tRNA (transfer RNA).

The building blocks of DNA, composed of a phosphate group, a 5-carbon sugar, and a nitrogen-containing base.

Adenine always pairs with thymine (or uracil in RNA), and guanine always pairs with cytosine.

The first step in the process of central dogma. It's the process of creating an mRNA copy from a DNA template.

The process of inserting specific genes into an organism's DNA to modify or create new traits.

Any change in the sequence of DNA.

A type of mutation where a single nucleotide is replaced with another.

A type of mutation where a nucleotide is inserted or deleted, shifting the reading frame of the DNA sequence.

The process of creating identical offspring from a single parent.

The process of creating offspring from the combination of genetic material from two parents.

The physical expression of a trait.

The genetic makeup of an organism.

A pattern of inheritance where the interaction of multiple genes contributes to a single phenotypic trait, resulting in a continuous range of variation. Eye color, height, and skin pigmentation are examples of polygenic traits.

A group of organisms that includes an ancestor and all of its descendants, representing a phylogenetic classification based on evolutionary relationships.

The preserved remains or traces of ancient organisms, often found in sedimentary rock layers.

A method used to determine the age of a fossil by measuring the amount of radioactive decay in the surrounding rocks or the fossil itself, providing a precise age.

A method used to estimate a fossil's age by analyzing its position within rock layers, with older fossils found in deeper layers. It provides a general timeline for the fossil.

A scientific concept proposed by Charles Darwin, explaining how organisms better adapted to their environment are more likely to survive and reproduce, passing on their advantageous traits.

The father of modern genetics, Gregor Mendel, conducted experiments using pea plants to discover fundamental laws of inheritance. He observed that alleles controlling traits separate during gamete formation (Law of Segregation) and genes for different traits are inherited independently (Law of Independent Assortment).

A dominant allele masks the expression of a recessive allele when present together in a pair. For example, if a pea plant inherits a dominant allele for purple flowers and a recessive allele for white flowers, it will display purple flowers.

The Law of Segregation states that allele pairs separate during gamete formation, meaning each gamete (sperm or egg) receives only one allele from the pair. This ensures that offspring inherit one allele from each parent.

The Law of Independent Assortment states that genes for different traits are inherited independently of each other. This means that the inheritance of one trait does not influence the inheritance of another trait.

A genotype refers to the specific genetic makeup of an individual, represented by the combination of alleles they possess. For example, a plant's genotype for flower color could be 'PP' (homozygous dominant for purple flowers), 'Pp' (heterozygous), or 'pp' (homozygous recessive for white flowers).

A phenotype is the observable physical or biochemical characteristics of an organism, determined by its genotype and environmental factors. For instance, the phenotype of the pea plant mentioned above would be 'purple flowers' for both 'PP' and 'Pp' genotypes, but 'white flowers' for the 'pp' genotype.

A homozygous genotype refers to an individual carrying two identical alleles for a particular trait. This can be either homozygous dominant (e.g., 'PP' for purple flowers) or homozygous recessive (e.g., 'pp' for white flowers).

A heterozygous genotype refers to an individual carrying two different alleles for a particular trait, one dominant and one recessive (e.g., 'Pp' for purple flowers). The dominant allele masks the effect of the recessive allele, resulting in the expression of the dominant trait.

A Punnett Square is a visual tool used to predict the possible genotypes and phenotypes of offspring resulting from a cross between two parents. It helps illustrate the inheritance patterns of alleles and the probability of offspring exhibiting different traits.

A Punnett Square is used to predict possible genotype combinations in offspring by combining alleles from each parent. The genotypes of the parents are placed along the top and side of the square, and each box represents a possible combination of alleles.