Genetics Vocabulary Study Guide

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Adaptation = a new and beneficial trait. Adaptations increase the ability of an organism to survive in its environment and produce offspring. Adaptations (new beneficial traits) arise from spontaneous mutations. Creatures don’t choose to change!

Amino acids = there are 21 different kinds of amino acids that make protein. (These are like bricks.) The sub-units that join together to make proteins.

Allele = A factor or letter that makes up a gene.  2 alleles make up one gene.

Alleles = "B" and "b" are different alleles.

Anticodon = A sequence of 3 letters found on TRNA that pairs with the codon of MRNA.

Autosomal = refers to genes that are not found on the sex chromosomes. Autosomal chromosomes are ones that are not XX and XY.

Bases = Adenine, Thymine, Guanine and Cytosine. A matches with T and G matches with C. The sequence of bases make up your genetic code.

Carrier = a person who has a recessive allele and a Dominant allele. In the case of Tay Sachs, a carrier would have this genotype: (Nn); the recessive allele is harmful. A brown-eye person who has a hybrid gene (Bb) can also be considered a carrier because the person carries the recessive allele for blue eye color, (b).

Chromosomes = 46 are found in human cells. Genes are carried among chromosomes.

Codon = A sequence of 3 letters on MRNA that code for amino acids. A codon can also tell when to start and stop translation.

Crick: Francis Crick and James Watson = Discovered DNA's famous double helix structure. Published in 1953. They won the Nobel Prize in 1962.

Cystic Fibrosis = Autosomal recessive. Mucous in lungs... Death in the 20s.

Cytoplasm = The part of the cell that lies outside of the nucleus. It is comprised of the cytosol and the organelles.

Darwin, Charles = developed The Theory of Natural Selection that states "those individuals who possess superior physical, behavioral, or other attributes are more likely to survive than those which are not so well endowed."

DNA = The main instructions that explain how to build the body. (Deoxyribose Nucleic Acid) DNA makes up alleles, genes and chromosomes.

Dominance = This is one of Johann Gregor Mendel’s principles. In his studies with pea plants Mendel notices that pure tall plants bred to pure short plants resulted in tall hybrid plants. Tallness was dominant to shortness.

Dominant = an allele that overpowers another is dominant. For instance, B overpowers and masks b. Brown eyes are dominant to blue eyes.

Down's Syndrome = due to an extra chromosome. (21st pair)

Evolution = any process of change over time. Evolution is a change in the traits of living organisms over generations, including the emergence of new species. Since the development of modern genetics in the 1940s, evolution has been defined more specifically as a change in the frequency of alleles in a population from one generation to the next. Evolution is change in the heritable traits of a population over many generations.

Fit = An organism that produces a large number of offspring is deemed fit. (Fitness has nothing to do with the size or strength of the critter-it is all about passing genes on. Frogs are fit. The Pope is not fit.)

Enzyme = A type of protein that controls the rate of a biochemical reaction.

Franklin, Rosalin = Her x-ray crystallography work with DNA was used (without her knowledge) to crack the structure the DNA double helix.

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Gamete = means sperm or egg. Germ Cell. In humans, a germ cell contains 23 chromosomes.

Gene = Every trait is controlled by a gene. A human has 20,000 genes. Genes are controlled by 2 factors called “alleles”. Each allele comes from a parent. Bb, NN and ee represent three genes.

Genotype = All the genes of a beastie equal the genotype of the beastie. (Genes an organism possesses)

Germ Cell- An egg or sperm cell. A gamete. In humans, a germ cell contains 23 chromosomes.

Hemophilia = sex-linked recessive. Males get it most often. XN Xn = carrier female. Xn Y = affected male.

Heterozygous = this means alleles of a gene are "different". See hybrid.

Homozygous = when alleles of a gene are "the same”. BB, nn, and ee are all homozygous.

Huntington's Chorea = Autosomal Dominant. People die at 40 +... Jerky muscular motions

Hybrid = means alleles of a gene are "different" (Hh) See heterozygous.

Hydrogen Bonds = connect bases in the DNA molecule. The bond results between a positive hydrogen atom in one molecule and an electronegative atom in the other.

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Independent Assortment: This is Johann Gregor Mendel’s 2nd principle. It states that alleles of one gene separate independently from alleles of another gene. In other words, eye color does not affect a person’s ability to roll his or her tongue.

Meiosis = the kind of cell division that produces sperm and egg. Meiosis cuts the number of chromosomes in half. In humans, for instance, the nuclei of body cells contain 46 chromosomes. Due to meiosis, sex cells carry only 23 chromosomes – one chromosome from each original homologous pair. 

Mendel, Johann Gregor = The father of genetics (said that traits are controlled by 2 factors etc...) 1866

Mitosis = the kind of cell division that splits an original cell into 2 identical daughter cells. Mitosis causes you to grow. Mitosis replaces old cells. Interphase is the resting phase. Prophase starts the process. The chromosomes and their copies line up at Metaphase. During Anaphase the chromosomal copies are separated. In telophase the chromosomes are very far apart. Cytokinesis forms two new cells.

MRNA = This type of RNA matches with DNA and then moves to the ribosome. Messenger ribonucleic acid. MRNA is transcribed from DNA and carries the instructions about how to make a protein to the ribosome.

Mutation = A change in the DNA instructions. A change in the DNA sequence. The change can be beneficial, detrimental or neutral. It ultimately results in a change in protein. For instance, random genetic mutation gave rise to the dark phenotype of the peppered moth.

Natural Selection = Darwin said that the process that eliminates creatures with inferior traits and preserves those with superior traits is known as natural selection.  Critters with good traits will be selected by nature to survive. Those organisms that survive are more likely to produce offspring with the same advantages for survival thus increasing the population of the organism. Critters with negative traits will die off.

Non-Disjunction: When homologous chromosomes fail to segregate properly during meiosis. Down syndrome, Turner syndrome and Klinefelter syndrome result from non-disjunction.

Nucleotide = One of the four DNA chemical submits: (A + sugar and phosphate), (T + sugar and phosphate), (G + sugar and phosphate), (C + sugar and phosphate). 3 billion nucleotides make up a human's genetic code.

Phenotype = the way an organism looks. The appearance.

Prenatal = means "before birth"

Protein = Skin, antibodies, muscle, hormones, are examples of protein (finished product) A long chain of amino acids. Enzymes, pigments etc.…

Recessive = A small, weaker allele is recessive.

Ribosome = this is where MRNA matches with TRNA and construction occurs. The site of protein construction. Ribosomes move along the MRNA as it is translated into protein.

Segregation = This is one of Mendel’s principles. Mendel said that all genes are comprised of 2 factors, one from each parent. Chromosomes segregate during meiosis. These factors (alleles) of a gene separate during the formation of gametes (sperm and egg). This ensures that each parent contributes 50% of their genetic information.

Sex chromosomes = chromosomes that determine sex (XY and XX)

Somatic Cell = Body cell that contains 46 chromosomes in humans.

Sugar = Deoxyribose sugar. Found in backbones of DNA helix. Attaches to bases (AT, GC). Alternates with phosphate in the backbones.

Tay Sachs = Autosomal recessive. Children die young. Head enlarges....

TRNA = This matches with MRNA and also carries an amino acid. (truck). Transfer ribonucleic acid. a type of RNA that carries an amino acid to the MRNA on the ribosome.

Trait = is a feature of an organism.  

Transcription = The process of copying DNA into MRNA

Translation = The process of converting MRNA into protein.

Uracil = in RNA, this base matches with Adenine instead of Thymine.

Variation = in any population of critters, some are different from the others. For instance, the variation within the peppered moth population allowed the species to survive under the changing environmental conditions. Variety! In a population, critters are different – due to mutations.

Watson: Francis Crick and James Watson = Discovered DNA's famous double helix structure. Published in 1953.

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