Document 64860

Milestone Minutes
Week 3
Write notes in your Milestone Journal and answer the practice
DNA 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
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
 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
 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
 Trisomy- condition of having an extra chromosome (Down Syndrome)
DNA technology can change the genetic makeup of an
genes from one
organism to another
Genetic Engineeringusing organisms for
beneficial purposes
(insulin production,
fighting viruses)
Complete the practice
questions in your

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