Practice your genetics vocabulary Genetics Unit Review Practice your genetics vocabulary

Gene A section of DNA that determines a trait OR… A set of instructions in the DNA to make a protein

Allele A form of a gene

Dominant allele The strong form of a gene When it is present, it hides the weaker allele

Recessive allele The weaker form of a gene

Phenotype The physical trait that an organism shows Examples: Tall, short or Curly hair

Genotype The 2 alleles that an organism has for a trait Examples: TT, Tt or tt

Incomplete Dominance When there are 2 alleles for a trait but neither completely hides the other There are 3 phenotypes Example: Hair texture: CC=curly, SS=straight, CS=wavy

Purebred When an organism has 2 of the same alleles for a trait Examples: TT or tt

Hybrid When an organism has 2 different alleles for a trait Example: Tt

Gametes Special cells that contain half the total number of chromosomes Also know as? sex cells, sperm or egg cells What kind of cell division makes gametes? Meiosis

Meiosis A type of cell division that produces cells with half the normal number of chromosomes Makes gametes How does meiosis help to create variety in offspring? Meiosis shuffles the chromosomes and creates different types of gametes. These different gametes will form offspring that are different from either parent.

Fertilization When the sperm and egg combine to form a new organism What is this first cell called? A Zygote What type of reproduction is this a part of? Sexual Reproduction

Sexual Reproduction A type of reproduction that requires 2 parents It produces offspring that are different from their parents and siblings. Examples: Mammals, flower producing plants

Asexual Reproduction A type of reproduction that requires only 1 parent It produces offspring that are identical to the parent. Example: Amoeba reproduce this way

Chromosome A tightly wound section of DNA that contains many genes How many chromosomes do humans have in each body cell? 46 or 23 pairs

What is this diagram showing you? DNA is stored in the nucleus A chromosome is made up of tightly wound DNA

Sex Chromosomes Humans have 2 chromosomes that determine sex X and Y chromosomes A person with XX is a? girl A person with XY is a? boy

Genetic Disorders What is an example of a genetic disorder that is caused by a dominant allele? Achondroplasia (form of dwarfism), polydactylism (more than 5 fingers) What is an example of a genetic disorder that is caused by a recessive allele? Phenyketonuria (PKU), Albinism, Sickle-cell anemia What is an example of a genetic disorder that is caused by a change in the number of chromosomes? Down Syndrome, Klinefelter and Turner Syndromes

Genetic Disorders What is a carrier? A person who has the allele for a disorder but who does not show the disorder Why can’t there be “carriers” for dominant allele disorders? A person cannot have a dominant allele and not show it. If the person has the dominant allele, they have the disorder.

Sex-linked Traits A trait whose gene is on the sex chromosomes, usually the X Examples: colorblindness, hemophilia Why are men more likely to have a sex-linked disorder? They only have 1 X chromosome so they do not have a backup copy if they get an allele that causes a disorder on their X chromosome

DNA Nucleotide A building block of DNA It’s common parts are: a sugar, a phosphate and a nitrogen base The 4 nitrogen bases are: Adenine (A) Thymine (T) Guanine (G) Cytosine (C) Which bases always pair up? A with T, C with G

DNA sequence DNA codes for proteins in the order of the? bases Here is one side of a DNA molecule: A T C G G G C T T What is the order of the bases on the other side of the DNA? T A G C C C G A A How many bases does that DNA sequence code for? 3

DNA Replication The process by which DNA copies itself What are the steps? 1) DNA unzips 2) Nucleotides then attach to each single strand 3) 2 identical strands are then formed

Protein Synthesis The process by which proteins are made What are the steps? 1) DNA must be transcribed into mRNA 2) mRNA is then read by a ribosome 3) Ribosomes translate the mRNA instructions into a chain of amino acids (protein)

Mutation A change in the DNA sequence which can change the protein that is made from the DNA instructions Give an example of a helpful mutation: 6th finger in pandas Give an example of a harmful mutation: hemophilia Give an example of a neutral mutation: blue eyes Give an example of a mutation that is both helpful and harmful: sickle cell anemia

Mutagen Substance or condition that can cause mutations Exposure to mutagens can cause cancer Examples? X-rays UV rays from sunlight Radiation Chemicals in pesticides and cigarette smoke