Biology Term 1: Introduction to Genetics - DNA, Chromosomes, Mitosis - PDF
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This document introduces fundamental concepts in biology, including genetics, DNA structure, and cell division processes such as mitosis and meiosis. It covers key terms like heredity, genes, and chromosomes, and provides information on how genetic information is organized and passed on. It also includes a definition of DNA and base pairings (A-T, G-C).
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**Biology term 1** **Introduction to genetics** **Definitions-** **Genetics-** the study of heredity **Heredity-** how traits are passed down from one generation to the next. Traits that are advantageous are passed down. **Variability-** different traits within a population **Adaptation-** str...
**Biology term 1** **Introduction to genetics** **Definitions-** **Genetics-** the study of heredity **Heredity-** how traits are passed down from one generation to the next. Traits that are advantageous are passed down. **Variability-** different traits within a population **Adaptation-** structure or behaviour that allows an organism to survive in its environment. **Genes-** the units of heredity, determine traits in an individual **Variation-** a result of heredity. Influences how individuals and a species can survive. **DNA 6/2-** [DNA stands for Deoxyribonucleic acid (ON EXAM)] DNA itself is in the nucleus of cells. **Structure of DNA-** - The base unit of DNA is a [nucleotide ] -phosphate backbone -sugar -nitrogenous base **Nitrogenous bases-** A= adenine T= thymine G= guanine C= cytosine A=T G=C (always paired up) 2 hydrogen bonds 3 hydrogen bonds DNA is a double helix -twisted ladder **Genes, chromosomes and DNA 10/2-** Deoxyribonucleic acid Deoxyribonucleic acid Deoxyribonucleic acid **Quick Questions-** 1. A nucleotide is the base unit of DNA (sugar, 2. Adenine, thymine, cytosine, guanine (A-T, G-C) **Chromosomes-** [long strands of generic information located in the nuclei of cells.] - A human cell has 46 chromosomes (22 pairs of autosomes and 1 pair of sex (XX/XY) - Each chromosomes have thousands of genes on it - A gene is a sequence of nucleotide bases that code for a specific person - Each gene codes for a different characteristic e.g. blood type, hair colour, eye colour - humans have 3,223 million base pairs, which we think is about 24,000 genes - the average human gene length is 27000 base pairs long (this means we think we know what 648 million base pairs do. - A karyotype is a diagram that shows all the chromosomes an individual possesses (remember, each species has a specific number of chromosomes. **Chromosomes 11/2** Cells Somatic gametes (body) (sex) 22 pairs 1 pair Chromosomes chromosomes (X+Y) -Total of 23 chromosome pairs -Chromosomes contain genes -karyotype=chromosomal map  Sister chromatics **Disorders=** **Monosomy-** only 1 chromosome present in one of the pairs. ex. Turner syndrome 23^rd^ chromosome. **Trisomy-** three chromosomes present at a pair. Ex. Down syndrome 21^st^ chromosome. **Mitosis 13/2-** -Cell division -Asexual reproduction -Produces 2 identical daughter cells **I nterphase --** majority of a cell's life **P rophase-** before stage (DNA is copied) **M** **etaphase-** chromosomes lined up in the middle **A naphase-** chromosomes pulled apart and away **T elophase-** new nucleolus forms at both ends -Cytokinesis- cytoplasm splits, becomes 2 cells **Intro to meiosis 17/2-** **Mitosis-** - Cellular replication - For growth and repair - 2 identical cells - 46 chromosomes - Somatic cells (body) **Meiosis-** - Formation of gametes (sperm and egg) - For sexual reproduction - Produces 4 unique cells (genetically different) crossing over occurs - 23 chromosomes total = no pairs \*HAPLOID\* - Testes in men - Ovaries in women
