Biology Chapter: Cells and Genetics

Cells

• Cells are the basic structural, functional, and biological units of all known living organisms.

Nucleus

• The nucleus is an organelle that holds an organism's genetic makeup.
• It contains chromosomes.
• It stores genetic information.
• It regulates gene expression.
• It controls replication.

Chromosomes

• Chromosomes are threadlike structures made of protein and a single DNA molecule.
• They carry genetic information from cell to cell.

Genes

• Genes carry information that determines traits (features).
• Traits are often inherited from parents.

DNA

• DNA (deoxyribonucleic acid) is a molecule that contains the genetic code unique to each individual.

Chromosomes/Karyotypes

• Chromosomes are threadlike structures made of protein and DNA.
• They carry genomic information from cell to cell.
• Humans have 46 chromosomes.
• Karyotypes are photos of a person's chromosomes arranged in pairs.
• Karyotypes are used to identify genetic disorders.
• Homologous chromosomes are pairs of chromosomes that have the same genes in the same order but may have slight variations in their appearance.
• They come from each parent.
• They have the same shape and size.

Genetic Inheritance

• Alleles are specific genes inherited from parents.
• Dominant traits are stronger and overrule recessive genes.
• Recessive genes need two copies to be expressed.
• Genotype is the specific combination of genes inherited from parents.
• Phenotype is the observable trait resulting from the genotype.

DNA and Mutations

• DNA has a double helix structure with nucleotides.
• G pairs with C, and A pairs with T.
• Mutations are changes in DNA.
• Types of mutations include point mutations, substitutions, subtractions, duplications, and translocations.
• Mutations can affect genes and proteins.
• They can cause diseases or alter traits.

Cell Division

• Mitosis creates two identical cells for growth.
• Meiosis creates four different cells for reproduction, halving the chromosome number.
• Haploid cells have one set of chromosomes (found in gametes like sperm and egg).
• Diploid cells have two sets of chromosomes (typical in body cells).

Genetic Modification and Artificial Selection

• Genetically modified organisms (GMOs) have altered genes, usually for human preferences.
• Examples include canola.
• Genetic modification directly changes DNA.
• Artificial selection breeds organisms with preferred traits over generations.

Transgenic Organisms

• Transgenic organisms contain genes from other species.
• This is achieved through genetic engineering.
• Improvements in resistance, growth, or production of valuable substances such as medicines are possible.

Natural Selection and Evolution

• Natural selection is the process where organisms with traits better suited to their environment survive and reproduce, passing on those traits.
• Examples include finch beak variations.
• Natural selection, selective breeding, and gene manipulation lead to new traits.
• Natural selection involves survival of the fittest and nature selecting genes needed for survival.
• Selective breeding involves breeding animals for specific human-preferred traits.
• Gene manipulation directly alters genes.