Chapter 8 Study Guide - Biology PDF

Learning Objectives 8.1 1. What is the genome? The genome is all of the genetic information of an organism, including both chromosomal and non-chromosomal DNA. 2. Examples of nonchromosomal genetic material: Plasmids (in bacteria) and mitochondrial or chloropl...

Learning Objectives 8.1 1. What is the genome? The genome is all of the genetic information of an organism, including both chromosomal and non-chromosomal DNA. 2. Examples of nonchromosomal genetic material: Plasmids (in bacteria) and mitochondrial or chloroplast DNA (in eukaryotic cells). 3. What is the bacterial genome composed of? The bacterial genome consists of a single circular chromosome plus plasmids. 4. What is a plasmid? A plasmid is a small, circular piece of DNA that replicates independently of the bacterial chromosome and often carries genes for traits like antibiotic resistance. 5. What composes the eukaryotic cell genome? Eukaryotic cell genomes are composed of chromosomal DNA plus organelle DNA (from mitochondria and, in plants/algae, chloroplasts). 6. Examples of eukaryotic organelles that have DNA: Mitochondria and chloroplasts. 7. What are the genomes of cells composed of? The genomes of cells are composed of DNA. 8. What are the genomes of viruses composed of? Viral genomes can be composed of DNA or RNA. 9. What is a chromosome? A chromosome is a thread-like structure of DNA and protein that carries genetic information. 10. Compare and contrast the chromosomes of bacteria and eukaryotic cells:  Bacterial chromosomes are typically circular, located in the nucleoid region, and bacteria usually have one chromosome. Eukaryotic chromosomes are linear, located in the nucleus, and eukaryotes usually have many chromosomes. 11. Describe bacteria and eukaryotic chromosomes as linear or circular: Bacterial chromosomes are circular. Eukaryotic chromosomes are linear. 12. Describe the location of bacterial and eukaryotic chromosomes: Bacterial chromosomes are located in the nucleoid. Eukaryotic chromosomes are located in the nucleus. 13. Describe the number of chromosomes in bacteria and eukaryotes: Bacteria generally have one chromosome. Eukaryotes have many chromosomes. 14. What is a gene? A gene is a segment of DNA that contains the necessary code to make a protein or RNA. 15. Classical meaning of a gene: Traditionally, a gene is defined as a unit of heredity that is passed from parent to offspring and determines specific traits. 16. Molecular meaning of a gene: At the molecular level, a gene is a sequence of nucleotides that codes for the production of a protein or RNA. 17. What does a gene contain? A gene contains the necessary code to make a protein or RNA. 18. Three types of genes: Structural genes (encode proteins), regulatory genes (control gene expression), and genes for RNA machinery (involved in protein synthesis). 19. What is a genotype? A genotype is the genetic makeup of an organism, the set of genes it carries. 20. What is a phenotype? A phenotype is the physical expression or characteristics of the genotype, influenced by both genes and environment. 21. What does “genotype leads to phenotype” mean? It means that the genetic makeup (genotype) determines the physical traits or behavior (phenotype) of an organism. 22. Structure of a DNA molecule: DNA is a double-stranded helix composed of nucleotides, each consisting of a sugar, phosphate, and nitrogenous base. 23. What is the basic unit of DNA? The nucleotide is the basic unit of DNA. 24. Three parts of a nucleotide: A sugar (deoxyribose in DNA), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine). 25. Name of the sugar in DNA: Deoxyribose. 26. How are DNA strands connected? One strand of DNA is connected through phosphate bonds between the sugars of adjacent nucleotides. 27. Direction of DNA strands: Nucleotides go from the 5’ to 3’ direction. 28. Purines and pyrimidines in DNA:  Purines are adenine (A) and guanine (G), while pyrimidines are thymine (T) and cytosine (C). 29. How are the bases in DNA connected? Bases on complementary DNA strands are connected by hydrogen bonds. 30. Base pairing in DNA: Adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). 31. What does antiparallel mean in DNA? It means the two strands of DNA run in opposite directions, with one going from 5’ to 3’ and the other from 3’ to 5’. 32. What is DNA replication? DNA replication is the process by which DNA makes an identical copy of itself before cell division. 33. What is semi-conservative replication? Semi-conservative replication means that each new DNA molecule consists of one original strand and one newly synthesized strand. 34. Main enzyme in DNA replication: DNA Polymerase III is the main enzyme responsible for synthesizing new DNA strands during replication. Learning Objectives 8.2 1. What is transcription? Transcription is the process of copying a segment of DNA into RNA. 2. What is translation? Translation is the process where the mRNA sequence is decoded to produce a protein. 3. Main enzyme in transcription: RNA Polymerase is the enzyme that synthesizes RNA from the DNA template. 4. Differences between DNA and RNA nucleotides: DNA contains deoxyribose sugar and thymine (T), while RNA contains ribose sugar and uracil (U) instead of thymine. 5. Is RNA single-stranded? Yes, RNA is generally single-stranded compared to the double-stranded structure of DNA. 6. Base pairing in RNA: In RNA, uracil (U) pairs with adenine (A) instead of thymine. 7. Types of RNA involved in translation: The three main types of RNA involved in translation are mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA). 8. Function of rRNA: Ribosomal RNA (rRNA) is a component of the ribosome and helps in the assembly of proteins. 9. Function of mRNA: Messenger RNA (mRNA) carries the genetic information from DNA to the ribosome for protein synthesis. 10. Function of tRNA: Transfer RNA (tRNA) brings the appropriate amino acid to the ribosome based on the codon sequence of the mRNA. 11. What is a codon? A codon is a sequence of three RNA nucleotides that codes for a specific amino acid. 12. What is a start codon? The start codon (AUG) signals the beginning of translation and codes for the amino acid methionine. 13. First amino acid in every protein: The first amino acid in every protein is methionine. 14. What is a stop codon? A stop codon signals the end of translation and does not code for any amino acid.