Passive transport Active transport Exocytosis Endocytosis Membrane Transport

Facilitated diffusion Membrane Transport Channel proteins and carrier proteins

Membrane Transport – Active transport requires energy to move molecules across a membrane. Lower solute concentration Higher solute concentration ATP Solute

*Active transport Example: sodium- potassium pump Membrane Transport

Electrogenic pump: *Some ion pumps generate voltage across membranes *Voltage *Membrane potential Membrane Transport

*Each cell membrane has characteristic set of carrier proteins Membrane Transport

Passive Transport (requires no energy) Active Transport (requires energy) DiffusionFacilitated diffusionOsmosis Higher solute concentration Lower solute concentration Higher water concentration (lower solute concentration) Lower water concentration (higher solute concentration) Solute Higher solute concentration Lower solute concentration ATP Solute Water Solute MEMBRANE TRANSPORT

Traffic of Large Molecules – Exocytosis is the secretion of large molecules within vesicles. Outside of cell Cytoplasm Plasma membrane

Traffic of Large Molecules – Endocytosis takes material into a cell within vesicles that bud inward from the plasma membrane.

*Phagocytosis Exocytosis *Pinocytosis *Receptor-mediated endocytosis Endocytosis Transport of large molecules Types of endocytosis found in animal cells:

Cellular Reproduction Cell division Functions of cell division: *reproduction *growth and development *repair

Cellular Reproduction In asexual reproduction: Single-celled organisms reproduce by simple cell division There is no fertilization of an egg by a sperm Asexual Reproduction FUNCTIONS OF CELL DIVISION Sea stars LM Amoeba African Violet

Sexual reproduction requires fertilization of an egg by a sperm using a special type of cell division called meiosis. Cellular Reproduction

Eukaryotic Chromosomes Chromosomes LM

Duplicated chromosomes (sister chromatids) TEM Tight helical fiber Looped domains TEM Centromere Nucleosome “Beads on a string” Histones DNA double helix Eukaryotic Chromosomes – The DNA in a cell is packed into an elaborate, multilevel system of coiling and folding. – Histones are proteins used to package DNA in eukaryotes. – Nucleosomes consist of DNA wound around histone molecules.

Chromosome Structure Chromosome Centromere Sister Chromatids

The Cell Cycle The cell cycle consists of two distinct phases  Interphase  Mitotic phase S phase (DNA synthesis; chromosome duplication) Interphase (90% of time) G1G1 Mitotic phase (M) (10% of time) Cytokinesis Mitosis G2G2

G1: Metabolism and growth End of G1: Cell signaled to divide S (synthesis): DNA is duplicated G2: Cell forms chromosomes, completes preparations for cell and nuclear division Interphase Nuclear envelope LM Plasma membrane Centrosomes (with centriole pairs) Chromatin INTERPHASE

Prophase and Prometaphase Chromosome, consisting of two sister chromatids Spindle microtubules Fragments of nuclear envelope Centrosome Centromere Early mitotic spindle PROPHASE

Metaphase, Anaphase, Telophase ANAPHASE METAPHASE TELOPHASE Spindle Daughter chromosomes Cleavage furrow Nuclear envelope forming

Cytokinesis Animal cells Plant cells

Sexual reproduction requires fertilization of an egg by a sperm using a special type of cell division called meiosis. Meiosis

MEIOSIS I Sister chromatids separate. MEIOSIS II Homologous chromosomes separate. INTERPHASE BEFORE MEIOSIS Sister chromatids Duplicated pair of homologous chromosomes Chromosomes duplicate. Pair of homologous chromosomes in diploid parent cell

Meiosis MEIOSIS I: Sister chromatids remain attached Pair of homologous chromosomes INTERPHASE Sister chromatids Homologous chromosomes pair up and exchange segments. Chromosomes duplicate. Pairs of homologous chromosomes line up. Pairs of homologous chromosomes split up. Nuclear envelope Chromatin Centromere Microtubules attached to chromosome Sites of crossing over Spindle Centrosomes (with centriole pairs) PROPHASE IMETAPHASE IANAPHASE I

TELOPHASE II AND CYTOKINESIS Sister chromatids separate ANAPHASE II Cleavage furrow TELOPHASE I AND CYTOKINESIS Two haploid cells form; chromosomes are still doubled. MEIOSIS II: SISTER CHROMATIDS SEPARATE PROPHASE IIMETAPHASE II During another round of cell division, the sister chromatids finally separate; four haploid daughter cells result, containing single chromosomes. Haploid daughter cells forming Meiosis

How do we account for genetic variation? *Independent assortment *Crossing over *Random fertilization Independent Assortment: Cross over:

Mitosis and Meiosis