Benchmark 3 Review Notes

Honors Biology

Asexual Reproduction

Only one parent required

Genetically identical offspring created

Uses MITOSIS to make clone organisms

No gametes used

Types of Asexual Reproduction

• Budding

• Vegetative

• Binary Fission

Used by yeast and hydra

Used by plants

Used by bacteria

QUESTION:

Which type of asexual reproduction is shown to the right???

Sexual Reproduction

• Gametes are produced by the process of meiosis– Crossing-Over of Meiosis I ensures genetic variation

between offspring– Gametes are HAPLOID cells (N)

• Egg and sperm unit to form a zygote– Zygote is the first DIPLOID cell (2N) of a new

individual. The zygote becomes a fully-formed individual through mitosis

Production of Gametes

If a somatic cell has 100 chromosomes. . .

• Cells undergoing MITOSIS will have 100 chromosomes each

• DIPLOID cells created

• Cells undergoing MEIOSIS will have 50 chromosomes each

• HAPLOID cells created

Genetics Review

Genotypes

• Two alleles for an autosomal trait

• HH – homozygous dominant

• Hh – heterozygous• Hh – homozygous

recessive

Phenotypes

• Physical characteristics

• Hh and HH create the same phenotype

Punnett Squares for Autosomal Traits

1. What percentage of children will have the dominant phenotype?

2. What percentage of children will have the recessive phenotype?

Sex-Linked Traits

• Carried on X-chromosome

• Recessive alleles cause disorders like colorblindness, hemophilia, and baldness

• Boys receive X-chromosome and its alleles from MOM

• Use a SPECIAL Punnett Square to predict

Sex-Linked Punnett Squares

1. What percent of males inherit the disorder?

2. What percent of females are carriers for the disorder?

Pedigrees

1. Study the pedigree to the right.

2. What kind of trait is shown? Explain. . .

DNA and RNA

• DNA is double-stranded

• Base pair rules:– A—T– C—G

• For ATT-CGA: what is the complementary DNA strand?

• RNA is single-stranded

• Makes a single-strand copy off an open DNA strand

• For ATT-CGA: what is the complementary RNA strand?

Functions

• DNA: contains thousands of genes written as nucleotide sequences

• Genetic code determined by DNA nitrogen base sequence

• Kept in the nucleus of eukaryotic cells

• RNA:

mRNA: carries gene information from nucleus to ribosome

rRNA (ribosome): site where mRNA instructions are read

tRNA: carries amino acid to ribosomes according to mRNA instructions

Steps of Protein Synthesis

TRANSCRIPTION: • DNA gene opens to attach mRNA nucleotides • mRNA copies DNA gene in the nucleus• DNA closes back up as mRNA exits

TRANSLATION: • mRNA attaches to a ribosome where tRNA

brings correct amino acids

Two Important Types of Gene TechnologyGene splicing

• Genes from an organism are removed and inserted into another organism

Example: inserting human insulin-producing gene in bacteria to produce insulin quickly and economically

Genetic Engineering

• Used to replace undesired genes of an organism with better ones

Example: Glow in the dark puppies are created by inserting the glowing gene from jellyfish into the dog DNA

Gel Electrophoresis

• Used to determine relatedness of organisms

• Separates DNA bands by size

• Shorter segments travel the furthest through the matrix

More Matching Bands = Closer Relatedness