Chapter 11 Genetics

Sec. 11-1The Work of Gregor Mendel

Key Concepts:

What is the principle of dominance? – Some alleles are dominant, others are recessive

What happens during segregation? – Alleles are separated so each gamete carries a single copy of each gene

When does segregation happen? – During gamete formation (meiosis)

Vocabulary:

Genetics – Scientific study of heredity

True-breeding – If allowed to self-pollinate, they would produce identical offspring

Trait – Specific characteristic

Hybrid – Cross between parents with different traits

Gene – Chemical factors that determine traits

Allele – Different forms of a gene

Segregation – separation [of alleles]

Gamete – sex cells

P – parent generation

F1 – First filial generation (child)

F2 – Second filial generation

Sec. 11-2 Probability and Punnett Squares

Vocabulary:

Probability – The likelihood that a particular event will occur

Punnett Square – Diagram showing the possible gene combinations that will occur in future generations

Homozygous – Two identical alleles for a particular trait (TT)

Heterozygous – Two different alleles for a particular trait (Tt)

Phenotype – Physical characteristics

Genotype – Genetic make-up

Sec. 11-3 Exploring Mendelian Genetics (Independent Assortment only)

Vocabulary:

Independent Assortment – Genes that segregate independently and do not influence each other’s inheritance patterns (seed size/shape vs. color)

Sec. 11-4 Meiosis

Key Concepts:

What happens during the process of meiosis? – Reduction division

What is the main event of the first meiotic division? – Prophase I

How is meiosis different from mitosis? – Mitosis produces two diploid (identical) cells; meiosis produces four haploid (different) cells

Vocabulary:

Homologous – Each of the four chromosomes that came from the male parent has corresponding chromosomes from the female parent

Diploid – A cell that contains both sets of homologous chromosomes (2N)

Haploid – A cell contains only a single set of chromosomes (single set of genes) (N)

Meiosis – Reduction division in which the chromosome number is halved through separation of homologous chromosomes

Tetrad – Each chromosome pairs with its corresponding homologous chromosome

Synapsis – The pairing of two homologous chromosomes during Prophase I

Crossing-over/Recombination – Exchanging of portions of chromatids – happens during tetrad

Sec. 11-5 Linkage and Gene Maps (Key Concept & Vocabulary only)

Key Concepts:

What structures actually sort independently? –Chromosomes assort independently, not genes

Vocabulary:

Gene Map – Shows the relative locations of each gene on a chromosome

Linkage – Genes are linked (show up together consistently) so no new combinations show up; no intermediate phenotypes

Chapter 12 DNA & RNA

Sec. 12-1 DNA (omit scientists & classic experiments)

Key Concepts:

What is the overall structure of the DNA molecule? – A DNA molecule, as discovered by Watson and Crick, is a double-helix (two strands wound around each other)

What are the three parts of a nucleotide of DNA? – DNA is made up of deoxyribose, phosphate, and a nitrogenous base

…of RNA? – Ribose, phosphate, and a nitrogenous base (Uracil instead of Thymine) – it is also one strand

Vocabulary:

Nucleotide – The basic make-up of DNA; it is made up of deoxyribose, phosphate, and a nitrogenous base

Base pairing – Hydrogen bonds can only form between certain base pairs—adenine with thymine, guanine with cytosine

Purines – Adenine and Guanine

Pyrimidines – Cytosine and Thymine

Chargaff’s Rules – [A] = [T] and [G] = [C]

Sec. 12-2 Chromosomes and DNA Replication

Key Concepts:

What happens during DNA Replication? - During DNA Replication, the DNA molecule separates into two strands, and then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template, or model, for the new strand

Vocabulary:

Chromatin - Eukaryotic chromosomes contain both DNA and protein, tightly packed together to form this substance

Histone - DNA of the chromatin is tightly packed around proteins called histones

Nucleosome – Nucleosomes are the reason this length can be achieved – each nucleosome is super-coiled; nucleosomes play a role in regulating how genes are read – changes which proteins are produced

Replication - Duplication of DNA before a cell divides (KEY CONCEPT: During DNA Replication, the DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template, or model, for the new strand

DNA Polymerase - The principle enzyme involved in DNA replication; it polymerizes individual nucleotides to produce DNA

Replication Fork - Thereplication forkis a structure that forms within the nucleus duringDNA replication. It is created byhelices, which break thehydrogen bondsholding the twoDNAstrands together. The resulting structure has two branching "prongs", each one made up of a single strand of DNA.

Sec. 12-3 RNA and Protein Synthesis

Key Concepts:

What are the three main types of RNA? - Messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA)

What is transcription? - During transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template (model) from which nucleotides are assembled into a strand of RNA

What is translation? - During translation, the cell uses information from messenger RNA to produce proteins

Translation Process:

  • RNA transcribed from DNA
  • mRNA molecule in the cytoplasm attaches to a ribosome
  • The ribosome forms a peptide bond between the first and second amino acids, methionine and phenylalanine
  • The chain continues to grow until it reaches a stop codon on the mRNA molecule

Vocabulary:

Messenger RNA (abbreviation: __mRNA__) - The RNA molecules that carry copies of instructions from genes; they serve as “messengers” to the rest of the cell

Ribosomal RNA (abbreviation: __rRNA__) - Ribosomes made up of several dozen proteins, as well as this form of RNA

Transfer RNA (abbreviation: __tRNA__) - During construction of a protein, this type of RNA transfers each amino acid to the ribosome as it is specified by coded messages in mRNA

Transcription - RNA molecules are produced by copying part of the nucleotide sequence on DNA into a complementary sequence in RNA

RNA Polymerase - During transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template (model) from which nucleotides are assembled into a strand of RNA

Promoter - The region of DNA that acts as the initial binding site for RNA polymerase

Intron - A stretch of DNA that interrupts a gene and does not contribute to the specification of a protein

Exon - Any segment of a discontinuous gene the segments of which are separated by introns

Codon - A sequence of three adjacent nucleotides constituting the genetic code that determines the insertion of a specific amino acid in a polypeptide chain during protein synthesis or the signal to stop protein synthesis

Translation - The process by which messenger RNA directs the amino acid sequence of a growing polypeptide during protein synthesis

Anticodon - A sequence of three adjacent nucleotides in transfer RNA that binds to a corresponding codon in messenger RNA and designates a specific amino acid during protein synthesis

Sec. 12-4 Mutations

Key Concepts:

What are gene mutations? - Two types of mutations:

  • Point mutations (substitutions)
  • Frameshift mutations (insertion/deletion) – can affect protein so that it is unable to perform properly

What are chromosomal mutations? - Chromosomal mutations change the number or structure of a chromosome:

  • Deletion
  • Duplication
  • Inversion
  • Translocation

Vocabulary:

Mutation - Changes in DNA sequence that affect genetic information

Point mutation - Mutations that affect one nucleotide; they occur in one specific place

Frameshift mutation - Mutations that shift the “reading frame” of the genetic message (i.e. deletion, insertion)

Chromosomal mutation (not bolded in text; see p. 308) - Chromosomal mutations change the number or structure of a chromosome: Deletion, Duplication, Inversion, and Translocation

Chapter 13 Biotechnology

Sec. 13-1 Changing the Living World

Sec. 13-2 Manipulating DNA

Sec. 13-3 Cell Transformation

Sec. 13-4 Applications of Genetic Engineering

Chapter 14 Human Genome

Sec. 14-1 Human Heredity

Key concepts:

How is gender determined? - All eggs carry a single X chromosome (23X). However, half of all the sperm cells carry an X chromosome (23X), while the other half carries a Y chromosome (23Y). This ensures that just about half of the zygotes will be 46XX and half will be 46XY

How do small changes in DNA cause genetic disorders? - In both cystic fibrosis and sickle cell disease, a small change in the DNA of a single gene affects the structure of a protein, causing a serious genetic disorder.

Vocabulary:

Karyotype – A picture of chromosomes taken during mitosis arranged in corresponding pairs

Sex Chromosome – Two chromosomes (X and Y) that determine an individual’s gender

Autosome – The remaining 44 chromosomes in human DNA

Pedigree – Chart that shows the relationships within a family, which can be used to help with the task of determining the inheritance of a trait

Sec. 14-2 Human Chromosomes

**Most sex-linked traits are recessive

**Most are located on the X-chromosome (passed by the mother)

Key concepts:

Why are sex-linked disorders more common in males than in females? - Males have just one X chromosome. Thus, all X-linked alleles are expressed in males, even if they are recessive

What is non-disjunction, and what problems does it cause? - If non-disjunction occurs, abnormal numbers of chromosomes may find their way into gametes, and a disorder of chromosome numbers may result (extra chromosomes, or deleted chromosomes)

Vocabulary:

Sex-linked gene – Genes located on sex chromosomes; many sex-linked genes are found on the X chromosome. More than 100 sex-linked genetic disorders have been mapped to the X chromosome.

Non-disjunction (“not coming apart”) – The most common error in meiosis where homologous chromosomes fail to separate

Sec. 14-3 Human Molecular Genetics (Key Concepts & Vocabulary only)

Key concepts:

What is the goal of the human genome project? – The human genome project is an attempt to sequence all human DNA (Francis Collin & Craig Venter)

What is gene therapy? – In gene therapy, an absent or faulty gene is replaced by a normal, working gene

Vocabulary:

DNA Fingerprinting – A powerful new tool for the identification of individuals; analyzes sections of DNA that have little or known function but vary widely from one individual to another

AP Biology Laboratory 7: Genetics of Drosophila (“fly packet”)

see especially Introduction & Background

  • Flies are
  • Cheap
  • Easy to maintain
  • Small
  • Breed quickly/live a short life
  • Can’t hurt you