Organism Traits (8th) Study Guide PDF

Organism Traits (8th) Study Guide Vocabulary: Adenine - the complementary nitrogenous base of DNA to thymine amino acid - molecules that combine to form proteins Chromosome - a structure found inside the nucleus of a cell that is made up of proteins and DN...

Organism Traits (8th) Study Guide Vocabulary: Adenine - the complementary nitrogenous base of DNA to thymine amino acid - molecules that combine to form proteins Chromosome - a structure found inside the nucleus of a cell that is made up of proteins and DNA. Cytosine - the complementary nitrogenous base of DNA to guanine double helix - the physical structure of DNA Gene - a section of DNA that codes for a trait Guanine - the complementary nitrogenous base of DNA to cytosine Mutation - A change in the usual DNA sequence at a particular gene locus Protein - A molecule made up of amino acids thymine - the complementary nitrogenous base of DNA to adenine Genotype - the genetic makeup of an organism Maladaptation - a trait that is (or has become) more harmful than helpful Phenotype - an individual's observable traits, such as height, eye color and blood type 1. Identify the location of DNA within the body. a. The nucleus 2. Explain the relationships between chromosomes, DNA, alleles, and genes. a. Chromosomes are made up of proteins and DNA in sections of genes b. Genes are made up of long strands of DNA. They code for proteins. c. Alleles are the chemical code for traits. 3. Explain how alleles can be dominant or recessive. a. Alleles are dominant when one allele suppresses the expression of the other. b. Suppressed alleles are recessive. 4. Relate the expression of dominant and recessive alleles to heterozygous and homozygous alleles. a. Homozygous: when the two alleles for a trait are the same. b. Heterozygous: when the two alleles for a trait are different. 5. Explain how base pairs of thymine, adenine, guanine, and cytosine compose the double helix structure of DNA. a. Adenine - Thymine b. Cytosine - Guanine c. The base pairs bond with hydrogen bonds d. They create the “ladder” rungs of DNA e. The bonding causes the two strands to spiral around each other in a shape called a double helix. 6. Explain the role of genes in the construction of specific amino acids, and therefore proteins.  a. Genes have the code that is transcribed into mRNA to build a specific protein. 7. Relate the construction of specific proteins with traits of an organ. a. A protein's amino acids determine its 3D shape and its functions in the cell, which in turn, affect an organism’s traits. 8. 8. Explain how mutations can affect the structure of DNA. a. Mutations result either from errors in DNA replication or from the damaging effects of mutagens, such as chemicals and radiation, which react with DNA and change the structures of individual nucleotides. 9. Explain how mutations can affect the structure of chromosomes. a. The result is the deletion of a DNA sequence in one chromosome, and the insertion of a DNA sequence in the other chromosome. In other cases, mutations alter the way a gene is read through either the insertion or the deletion of a single base. 10. Explain how mutations of DNA or chromosomes affect the production of proteins within an organism, and therefore the organism itself. a. Such mutations lead to either the production of a different protein or the premature termination of a protein. 11. Give an example of a mutation having a harmful effect on the structure or function of an organism. a. Harmful mutations can lead to hereditary diseases, such as Huntington’s disease, cystic fibrosis, sickle cell anemia, and even certain cancers. 12. Give an example of a mutation having no effect on the structure or function of an organism. a. Silent mutations are base substitutions that result in no change of the amino acid or amino acid functionality when the altered messenger RNA (mRNA) is translated. For example, if the codon AAA is altered to become AAG, the same amino acid – lysine – will be incorporated into the peptide chain. 13. Give an example of a mutation having a beneficial effect on the structure or function of an organism. a. Mutations can be beneficial to an organism and in germline mutations affect their offspring and their populations in a positive way. Though it doesn’t help humans, mutations in bacteria led to their resistance to certain antibiotics over time. A mutation that benefits humans is the resistance to malaria that people with a mild form of sickle cell anemia (HbC hemoglobin) experience. 14. Explain the difference between phenotype and genotype. a. Genotype is the chemical code for a trait (Ex. TT, Tt, tt) b. Phenotype is the physical representation of that trait. (Ex. curly hair) 15. Describe different phenotypes a. Hair, eye color, etc. 16. Explain how phenotypes are influenced by genotypes. a. Genotypes code for phenotypes. Genotypes are the code for the phenotype. 17. Explain how phenotypes adapt to environmental factors. a. Changes in length of day (amount of light) signals the changes in gene expression. i. Example: Snowshoe Rabbit turns white in winter and brown in summer 18. Explain how the adaptation of a phenotype to one environment can become a maladaptation if the environment changes.  a. For example: a phenotype to binge eat in a highly competitive versus non competitive environment. Wolves in the wild vs. Domesticated Wolves. 19. Explain how genes determine which traits are expressed by organisms. a. Genes in the DNA are transcribed into mRNA. mRNA takes the transcription to the rRNA or ribosome, and where tRNA matches its anticodons with the mRNA codons. The tRNA then attaches its amino acid to the polypeptide chain to create a protein. This protein determines an organism's traits. 20. Explain how environmental factors can affect organism growth. a. Example: people in countries where they may not have access to proper nourishment may be shorter or underweight. 21. Debate whether “nature” or “nurture” has a larger impact on an organism’s traits. a. For example, construct an argument for whether environmental factors or an organism’s genes ultimately play a more important role in its survival.