BIOL 145 - Week 5 - Simpson college

Annual plants

Cycle completed in single season

Biennial plants

Cycle completed in two growing seasons

Perennial plants

Cycle takes several to many growing seasons or plant produces flowers on new growth, while other plant parts persist indefinitely

There are two major classes of flowering plants

Magnoliopsida (dicots) & Liliopsida (monocots)

Flowers occur as specialized branches at

Tips of peduncles or pedicels (stalk of single flower)

Receptacle

Swollen end of peduncle or pedicel

What is collectively called corolla

Petals

What is called a calyx

Sepals

What are calyx and corolla called together

Perianth

Superior Ovary

Calyx and corolla attached to receptacle at base of ovary

Inferior Ovary

Receptacle grows up and around the ovary

Carpel

Leaf with ovules on margins

Inflorescence

Group of flowers on a body

Exocarp

Skin

Endocarp

Inner boundary around seed(s)

Mesocarp

Tissue between exocarp and endocarp

Mesocarp, endocarp, and exocarp can be called together what?

Pericarp

Fleshy Fruits

Mesocarp at least partly fleshy at maturity

Simple fleshy fruits develop from

Flower with single pistil

Drupe

Simple fleshy fruit with single seed enclosed by hard, stony endocarp (pit)

Hesperidium

Berry with a leathery skin that contains oils

True berry

With thin skin and relatively soft pericarp

Berries

From compound ovary, with more than one seed, and with fleshy pericarp

Pepo

Relatively thick rind

Dry Fruits

Mesocarp dry at maturity

Dehiscent fruits

Split at Maturity

Capsules

Consist of at least two carpels, and split in a variety of ways

Aggregate Fruits

Derived from single flower with several to many pistils (raspberries)

Cotyledons

Food storage organs that function as “seed leaves”

Embryo

cotyledons and plantlet

Plumule

Embryo shoot

Epicotyl

Stem above cotyledon attachment

Hypocotyl

Stem below cotyledon attachment

Radicle

Tip of embryo that develops into root

Germination is

beginning or resumption of seed growth

After ripening (seed germination)

Embryo composed of only of few cells when fruit ripens; seeds will not germinate until embryo develops

Scarification

Artificially breaking dormancy

Epigeous germination

Hypocotyl lengthens, bends and becomes hook-shaped. Top of hook emerges from ground, pulling cotyledons above ground.

Hypogeous germination

Hypocotyl remains short and cotyledons do not emerge above surface

Asexual reproduction

Production of cells identical in chromosomes with cells from which they arose

Homologous chromosomes =

chromosome pairs

Meiosis: Division I (Meiosis I or Reduction Division)

Number of chromosomes reduced to half

Meiosis: Division II (Meiosis II or Equational Division)

No further reduction in chromosome number

Sporophytes develop from

zygotes and produce sporocytes

Sporocyte undergoes meiosis

Produces 4 haploid spores

Gametophytes develop from

Spores

Rule 1 for Alteration of Generations

First cell of gametophyte generation is a spore, and last is a gamete

Rule 2 for Alteration of Generations

Any gametophyte cell contains half the chromosomes as the sporophyte generation

Rule 3 for Alteration of Generations

First cell of sporophyte generation is a zygote, and last cell is a sporocyte

Rule 4 for Alteration of Generations

Any sporocyte cell contains twice as many chromosomes as the gametophyte generation

Rule 5 for Alteration of Generations

Change from sporophyte to gametophyte generation occurs as a result of meiosis

Rule 6 for Alteration of Generations

Change from gametophyte to sporophyte occurs as a result of fertilization.

Chromosomes composed two types of large molecules

DNA and protein

RNA

Contains ribose, instead of deoxyribose sugars; single stranded; thymine replaced by uracil

Translation

RNA translated to produce proteins

Messenger RNA (mRNA)

Translated to produce proteins

Transfer RNA (tRNA)

Machinery for translation

Ribosomal RNA (rRNA)

Machinery for translation

Promoter

Region at beginning of every gene signals transcription enzymes to begin copying gene

Terminator

DNA sequence at end signals transcription enzymes to fall off

Mutations are

changes in a DNA sequence

Mutagens

Agents that alter DNA sequences

Mutagens examples

Ultraviolet light, Ionizing radiation, Certain chemicals

Aneuploid

Carries one or more extra chromosome(s), or is missing one or more chromosome(s)

Polyploid

Has at least one complete extra set of chromosomes

Gregor Mendel help create what?

PUNNETT SQUARE

Homozygous

Both alleles identical

Heterozygous

Alleles are contrasting

Phenotype

Organism’s physical appearance

Genotype

Genetic information responsible for contributing to phenotype

Law of dominance

For any given pair of alleles, one (dominant) may mask the expression of the other (recessive)

Law of unit characters

Factors (alleles), which always occur in pairs, control the inheritance of various characteristics. Genes are always at the same position (locus) on homologous chromosomes

Monohybrid cross

F1 plants intercrossed to produce F2 generation

Dihybrid cross

Start with parents differing in two traits

Law of independent assortment

Factors (genes) controlling two or more traits segregate independently of each other

Testcross

Cross between a plant having a dominant phenotype with a homozygous recessive plant

Why a testcross

Determine whether plant with dominant phenotype is homozygous or heterozygous

Backcross

A cross between a hybrid and one of its parents

Quantitative traits exhibit

Range of phenotypes rather than discrete phenotypes as studied by Mendel

Extranuclear DNA

In mitochondria and chloroplasts

Linked genes

Genes together on a chromosome

Hardy-Weinberg law

Proportions of dominant alleles to recessive alleles in a large, random mating population will remain same from generation to generation in the absence of forces that change those proportions

Forces that can change proportions of dominant to recessive alleles

Small populations & Selection

Selection

Most significant cause of exception to H-W (Hardy-Weinberg Law)

Small populations

Random loss of alleles can occur if individuals do not mate as often