Hypothesis-Driven Science– As a formal process of inquiry, the scientific method

consists of a series of steps.• The key element of the scientific method is

hypothesis-driven science.

Observation Question Hypothesis Prediction Experiment

Revise and repeat

Reporting the Results of Experiments

• Abstract• Introduction• Materials and Methods• Results• Discussion• Literature Cited

A scientific research report is a form of communication in which the investigator succinctly presents and interprets data collected in an investigation.

Introduction• General background information relevant to the topic• Information specific to your hypothesis• A short description of the hypothesis• A description of how you proposed to test the

hypothesis• Predictions of expected supportive for falsifying

results

Cellular ReproductionCell division- A process in which a cell divides into 2 or more cells.

Functions of cell division:*reproduction (at the cellular level and organismal level) *growth and development *repair

Mitosis- The process of nuclear division that results in two daughter nuclei genetically identical to the parent nucleus.

Chromosome Structure●Chromosome

unduplicated vs. duplicated● Centromere● Sister Chromatids

(a)

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(b)

(c)

(d)

Phases of Mitosis

A. Interphase B. ProphaseC. Metaphase D. Anaphase E. Telophase

Cellular ReproductionIn asexual reproduction:Formation of new individuals from cell(s) of a single parent resulting in offspring that are genetically identical to the parent.

Asexual ReproductionFUNCTIONS OF CELL DIVISION

Sea stars

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Amoeba African Violet

Sexual reproduction requires fertilization by the fusion of gametes, producing offspring that are genetically distinct from both parents.

Cellular Reproduction

MeiosisMeiosis – A type of cell division in which one diploid parent cell (2n) produces four haploid (n) daughter cells.

• Haploid – cell or organism that contains one complete set of chromosomes (n).

• Diploid - cell or organism that contains two complete sets of chromosomes (2n).

Meiosis

MEIOSIS I

Sisterchromatidsseparate.

MEIOSIS II

Homologouschromosomesseparate.

INTERPHASE BEFORE MEIOSIS

Sisterchromatids

Duplicated pair ofhomologouschromosomes

Chromosomesduplicate.

Pair of homologouschromosomes indiploid parent cell

MeiosisMEIOSIS I:

Sister chromatidsremain attached

Pair ofhomologouschromosomes

INTERPHASE

Sisterchromatids

Homologouschromosomespair up andexchangesegments.

Chromosomesduplicate.

Pairs of homologouschromosomesline up.

Pairs of homologouschromosomessplit up.

Nuclearenvelope

Chromatin

Centromere

Microtubulesattachedto chromosome

Sites of crossing over

Spindle

Centrosomes (with centriolepairs)

PROPHASE I METAPHASE I ANAPHASE I

TELOPHASE II AND

CYTOKINESIS

Sister chromatidsseparate

ANAPHASE II

Cleavagefurrow

TELOPHASE I AND

CYTOKINESIS

Two haploidcells form;chromosomesare stilldoubled.

MEIOSIS II: SISTER CHROMATIDS SEPARATEPROPHASE II METAPHASE II

During another round of cell division, the sisterchromatids finally separate; four haploiddaughter cells result, containing single

chromosomes.

Haploid daughtercells forming

Meiosis

Metaphase I

Metaphase II

Recombinant chromosomes

Gametes Recombinant chromosomescombine geneticinformation fromdifferent parents.

Homologous chromatidsexchange correspondingsegments.

Sister chromatids remain joined at theircentromeres.

Prophase Iof meiosis

Duplicated pair ofhomologouschromosomes

Chiasma, site ofcrossing over

Spindlemicrotubule

Crossing overIn crossing over:

•Homologous chromosomes exchange genetic information •Genetic recombination, the production of gene combinations different from those carried by parental chromosomes, occurs

MeiosisHow do we account for genetic variation?

*Independent assortment *Crossing over *Random fertilization

Independent Assortment:

Cross over:

Mitosis and Meiosis

Energy, Catalysis and BiosynthesisMetabolism

*catabolism

*anabolism

Complexity of metabolism

*potential energy

Enzymes–Metabolism is the total of all chemical reactions in an organism.–Most metabolic reactions require the assistance of enzymes, proteins that speed up chemical reactions.

Induced Fit

Enzymes

Enzymes

Substrate

Substrate

Substrate

Active site

Active site

Active site

Inhibitor

Inhibitor

Enzymes Physical and chemical properties affect enzyme activity:

*inhibitors

*cofactor*coenzyme

*activators