Chapter 11 Genetics
Sec. 11-1 The 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 - The replication fork is a structure that forms within the nucleus during DNA
replication. It is created by helices, which break the hydrogen bonds holding the
two DNA strands 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:
o RNA transcribed from DNA
o mRNA molecule in the cytoplasm attaches to a ribosome
o The ribosome forms a peptide bond between the first and second amino acids,
methionine and phenylalanine
o 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
o Cheap
o Easy to maintain
o Small
o Breed quickly/live a short life
o Can’t hurt you