Milestone MinutesGeneticsWeek 3

Write notes in your Milestone Journal and answer the practice questions.

GeneticsDNA and RNA are molecules essential for the transmission of

genetic information.

DNA is a double stranded helix, contains the sugar deoxyribose, A-T & G-C

RNA is single stranded, contains the sugar ribose, A-U & G-C, produces proteins

DNA replication (copying)occurs prior to mitosis during the cell cycle

Mitosis stages: prophase, metaphase, anaphase, telophase

Mitosis results in two genetically identical daughter cells, occurs in autosomal cells, diploid (asexual)

Meiosis results in four genetically different gametes (egg & sperm), haploid (sexual)

Recombination of genetic material (crossing over) occurs during anaphase 1 & 2 of meiosis

Mendel was the father of genetics and put forth laws concerning heredity.

Law of Dominance -dominate alleles (capital letter) suppress recessive alleles (lowercase letter)

Law of Segregation -during fertilization gametes randomly pair to produce four sets of alleles (monohyrid)

TT=homozygous dominant, Tt=heterozygous, tt=homozygous recessive Genotype is the combination of alleles, Phenotype is the physical expression of

alleles Law of Independent Assortment -genes for traits are inherited independently of

each other (dihybrid) Segregation & Independent Assortment allow only one allele a gene to be

present in the gametes

Alterations (mutations) can occur during meiosis and change the genetic code.

Some environmental factors are mutagenic (sunlight, chemical waste, radiation, toxins)

Insertion-addition of one or more nucleic bases in the genetic sequence, changes reading frame

Deletion-removal of one or more nucleic bases in the sequence, changes reading frame

Substitution-switch of one or more nucleic bases in the genetic sequence, no change to reading frame

Nondisjunction- failure of homologous chromosomes to separate during anaphase of meiosis

Trisomy- condition of having an extra chromosome (Down Syndrome)

DNA technology can change the genetic makeup of an organism.

Recombination-moving genes from one organism to another

(cross-pollination/Hybrids)

Genetic Engineering- using organisms for beneficial purposes (insulin production,

fighting viruses)

Complete the practice questions in your

journal.