Genetics

Vocabulary Allele – a pair of chromosomes Dominant – a gene that is always expressed (seen) Gene – a part of a chromosome made up of DNA Hybrid – Having two different types of genes for a particular trait

Vocabulary Offspring – new individuals produced as a result of reproduction Purebred – Having two identical genes for a trait Recessive – Genes that are hidden by dominant genes, there must be two of them for the trait to be expressed (seen) Traits – characteristics of an organism

Chromosomes: Made up of several ___________ (unit of _______________ for a particular trait) All human cells have ______ pairs (46) except sex cells have _____ total A pair (______________) determines the trait expressed Genes Hereditary 23 23 Allele

DNA: Structure: _______________ helix (twisted ladder) Makes up __________ Double Genes

Genetics: Mendel A. Studied ______ plants height, seed color, and seed shape Pea

Genetics: Hides Capital 1 gene Hidden Dominant Two B. Dominant Genes 1. __________ or mask another trait 2. Written as a _________ letter Ex. Tall = T 3. Only ______ needs to be present for the trait to be expressed Ex. Tall = TT or Tt C. Recessive Genes 1. ____________ by dominant genes 2. Written as the lower case letter of the _________ trait Ex. Short = t 3. ______ are needed for the trait to be expressed Ex. Short = tt Hides Capital 1 gene Hidden Dominant Two

Genetics: Homozygous Same Heterozygous Different Alleles separate D. Purebred 1. Also known as _______________________ 2. Having the __________ genes for a trait E. Hybrid 2. Having __________________ genes for a trait F. Principle of segregation 1. States ____________ (gene pairs) separate during meiosis (formation of gametes) 2. Nondisjunction - occurs when part or all of a chromosome does not _____________ during meiosis resulting in too many or too few chromosomes in an egg or sperm cell ex. Trisomy 21 (Downs Syndrome) Homozygous Same Heterozygous Different Alleles separate

Punnett Squares: Grid used to determine gene pairs of ________________ Example: Tt x Tt 1. Draw the square 2. Place one parent at the top of the square (one gene above each box) and the other parent to the left of the square (one gene next to each box). 3. Write in the top genes in each box below them. 4. Write in the side genes in each box to the right of them. Be sure that the capital letter is written first in each box. Offspring

Punnett Squares: 5. Determine the genotypes and express as a ratio or percent. Dominant : Hybrid : Recessive 1 : 2 : 1 Purebred Purebred 25% Purebred Tall, 50% Hybrid Tall, and 25% Short 6. Determine the phenotypes and express as a ratio or percent. Dominant : Recessive 3 : 1 75% Tall and 25% Short

Genetics: Incomplete Dominance A. ____________ of two traits B. Example: Four o’clock flowers Blending

Variation: Causes: A. Sexual Reproduction - offspring appear different from parents due to inheriting _________ from both parents B. Nondisjunction - Part or all of a chromosome doesn’t separate during ____________ C. Mutation - a change in DNA causing a change in a ______ Genes Meiosis Trait

Sex Determination Sex chromosomes are the 23rd pair Females have two x chromosomes Males have an x and a y chromosome

Sex Linked Traits Traits located on the upper portion of the x chromosome Ex. Colorblindness, baldness, hemophilia They are recessive traits, so they won’t be expressed (seen) if there is a dominant gene without the trait present

Females and Sex Linked Traits Inherit 2 dominant x’s without the trait (don’t exhibit the triat) Hybrid – inherit 1 dominant x without the trait and 1 recessive x with the trait (called a carrier – does not exhibit the trait but can pass it to their offspring) Inherit 2 recessive x’s with the trait (exhibits the trait) Rare for females to have sex-linked traits because they need to inherit 2 recessive x’s

Males and Sex Linked Traits Inherit 1 dominant x without the trait (don’t exhibit the trait) Inherit 1 recessive x with the trait (exhibits the trait) Males can not be carriers because they only have 1 x gene (y doesn’t have genes for these traits) Higher percentage of males with sex linked traits because they only need to inherit 1 recessive x to exhibit the trait

Pedigree Chart: Shows inheritance of ___________ through generations Traits

Genetic Engineering: Altering an organisms genetic material to affect its ____________ ________________ breeding - breeding organisms with specific traits Cloning - creating new organisms from cells of _______ organism Uses - food production and _______________ Traits Selective One Medical Purpose

A gene is inserted into a fertilized egg so that the organism that develops will have that trait Example: Inserting the gene that allows fish to survive in icy waters into tomato seeds so that the tomatoes can survive a frost

Remove the nucleus from a skin cell (full set of chromosomes) Remove the nucleus from an egg cell Insert the skin cell nucleus into the empty egg so it has a full set of chromosomes Egg will divide to produce an identical copy of the organism that the skin cell came from Cloning is a type of asexual reproduction

Review - Heat Conduction – heat transfer by direct contact ex. Frying an egg Convection – heat transfer within fluids (liquids and gases) ex. Boiling water Radiation – heat transfer through empty space ex. Warming hands by a campfire

Review – Phase Changes Melting – solid to a liquid, heat absorbed Freezing – liquid to a solid, heat released Condensation – gas to a liquid, heat released Evaporation or Vaporization (Boiling) – liquid to a gas, heat absorbed Sublimation – solid to a gas (no liquid phase), heat absorbed Deposition – gas to a solid (no liquid phase), heat released