Science Semester 2 Exam Study PDF

Basic Genetic Concepts, Chromosomes and Karyotypes Cells: The cell is the basic structural, functional, and biological unit of all known living organisms. Nucleus: The nucleus is an organelle that holds the genetic makeup of the organism and contains the chromosomes of the organism. The nucleus st...

Basic Genetic Concepts, Chromosomes and Karyotypes Cells: The cell is the basic structural, functional, and biological unit of all known living organisms. Nucleus: The nucleus is an organelle that holds the genetic makeup of the organism and contains the chromosomes of the organism. The nucleus stores genetic information, regulates gene expression, and controls replication. Chromosome: Chromosomes are threadlike structures made of protein and a single molecule of DNA that serve to carry the genomic information from cell to cell. Gene: Genes carry the information that determines ones traits, which are features usually from the parents. DNA: DNA or deoxyribonucleic acid is a molecule that contains the genetic code that is unique to every individual Chromosomes/Karytypes - Chromosomes are threadlike structures made up of protein and a single molecule of DNA that serve to carry the genomic information from cell to cell. - There are 46 chromosomes in a human cell. - Karyotypes are a photo of ones specific chromosonial structure referred to into pairs. - These photos are crucial as one is able to examine all 46 chromosomes and are able to determine illnesses and conditions. Homologous chromosomes are pairs of chromosomes that come from each parent and have the same genes in the same order, but with slight variations, they also are the same shape and size. Genetic Inheritance: - Alleles are a specific gene usually inherited from ones parents. An example is blue eyes. - Dominant traits describe alles that are stronger and overrule the “recessive gene”. A recessive allele is masked by a dominant allele, and both copies of the recessive allele must be present to express the trait. - A person's genotype is the specific combination of genes inherited from their parents. This is often described by the letter combination of both recessive and dominant alleles. The phenotype however is the observable trait as a result of the genotype, such as brown hair. DNA and Mutations Structure and function of DNA Structure of DNA (double helix - composed of nucleotides and complementary base pairing) Each molecule of DNA is a double helix formed from two complementary strands of nucleotides held together by hydrogen bonds between G-C and A-T base pairs. Types of mutations (e.g., point mutations, substitution) In total there are four types of mutations, these include, substitution, subtraction, duplication and translocation. Effects of mutations on genes and proteins: Mutations in genes can change how proteins work. These changes can lead to diseases or affect traits, making proteins not work correctly or causing them to behave differently in cells. Cell Division: Differences between mitosis and meiosis, outcomes & differences: Mitosis makes two identical cells for growth, while meiosis creates four different cells for reproduction. Mitosis keeps the chromosome number the same; meiosis halves it for genetic variety. Haploid vs. diploid cells Haploid cells have one set of chromosomes, found in gametes (sperm and egg). Diploid cells have two sets, one from each parent, and are typical in most body cells. Gametes: Gametes are reproductive cells (sperm and egg) with half the chromosome number, combining during fertilization to form a zygote. Genetic Modification and Artificial Selection: Definition and examples of genetically modified organisms (GMOs): Genetically modified organisms or GMOs are specific organisms that genes have been altered mainly for preference for humans. A common example could be canola. Differences between genetic modification and artificial selection Genetic modification is the changing/altering of specific genes, whilst artificial selection keeps the original traits but breed for preference of people. Transgenic organisms and their characteristics: Transgenic organisms contain genes from other species. They are created through genetic engineering to express new traits, such as improved resistance, growth, or the production of valuable substances like medicines. Similarities and differences between genetic modification and artificial selection: Both genetic modification and artificial selection aim to improve traits. Genetic modification directly alters DNA, while artificial selection breeds organisms with desired traits over generations through natural reproduction. Natural Selection and Evolution Theory of natural selection: The theory of natural selection, proposed by Charles Darwin, states that organisms with traits better suited to their environment are more likely to survive, reproduce, and pass those traits to offspring. Examples of natural selection (e.g., finch beak variation) Historical processes leading to new traits (e.g., natural selection, selective breeding, gene manipulation): New traits arise from natural selection, survival of the fittest and nature's selection of genes needed for survival. Selective breeding, the breeding of animals for desirable traits preferred by humans and gene manipulation, the direct altering of genes.