The Cell Cycle & Cell Division

Basic Understanding Structure – An arrangement or organization of parts to form an organ, system, or living thing. Characteristics – pertaining to, constituting, or indicating the character or peculiar quality of a person or thing

Basic Understanding Response –any behavior of a living organism that results from an external or internal stimulus. Stimulus - Something that can elicit or evoke a physiological response in a cell, a tissue, or an organism Species –composed of related individuals that resemble one another, are able to breed among themselves

Basic Understanding Development – the act or process of growth or progress Function – to perform a specified action or activity; work Mobility – The ability to move from place to place, job to job, or level to level.

Basic Understanding Extinction – a coming to an end or dying out Hierarchy –any organized system of things ranked one above another in successive order

Robert Hooke English Naturalist Was the first to use the term cell. Was looking at CORK under a compound microscope.

What is a cell? I t is the smallest unit of life that carries out life functions

The Cell Theory The cell is the basic unit of structure and function (a.k.a. – life) All living things are made up of 1 or more cells Cells come from other, preexisting cells (a.k.a. – reproduction)

Francesco Redi – The Italian Doctor It was previously thought that maggots spontaneously grew. Redi disproved this theory. He took 8 jars of rotting meat and covered 4 with muslin (fabric). The jars with muslin developed no maggots but the open jars had maggots. This is important because cells come from other cells.

Prokaryote Are unicellular - 1 Have no formed nucleus Are very disorganized. Have a cell wall, cytoplasm, ribosomes, bacteria have cell membrane Bacteria are prokaryotes

Eukaryote Have a Nucleus Have cell membrane bound organelles Are very organized. Can be singular or multi- cellular. Have these other organelles; nuclei, mitochondrion, lysosome, golgi apparatus, ribosomes

What’s Inside? Organelles –tiny structures within a cell that perform specific jobs to keep the cell alive

Cytoplasm - gel-like material inside cells Cytoplasm

Contains materials involved in cell metabolism. Gives the cell its shape

Cell Membrane - protects cell and controls what enters and leaves the cell. Cell Membrane

The Cell Membrane Is semi- permeable, or selectively permeable. Is made of a phospho-lipid bi- layer. Helps maintain the shape of the cell.

Nucleus - directs cell activities (brain) Nucleus

The Nucleus and The Nucleolus Serves as the control center of the cell and contains Deoxyribonucleic Acid (DNA) Nucleolus- Contains RNA Nuclear membrane – Control what goes in or out of the Nucleus.

Endoplasmic Reticulum (ER) - movement of materials throughout cell ER

Endoplasmic Reticulum Rough ER contains Ribosome's. Smooth ER has no Ribosome's

Ribosome - makes proteins Ribosomes

Ribosome's Grain like Structures Sites of protein synthesis

Mitochondria - the powerhouse of the cell (converts food into energy for the cell) Mitochondria

Makes ATP/ Energy These organelles are more plentiful in active cells

Chromatin/Chromosomes (DNA) - contains genetic information (inside the nucleus) Chromatin is the combination of DNA and proteins that make up the contents of the nucleus of a cell

Chromosomes Contains code that guides all cell activities They are found in the nucleus. Chromosomes contain the genes that determine an organisms characteristics.

The Centrioles Involved in cell division Produce Microtubules that pull chromosomes apart. Microtubules also give the cell structure. Are found inside the nucleus.

Golgi Body - packages and moves proteins Golgi Body

Golgi Bodies Look like stacks of pancakes.

Lysosome - digests wastes Lysosome

Lysosomes Powerful chemicals that break things down.

Vacuole - storage of food and water Vacuole

Vacuoles Plays a role in intercellular digestion Store food and water. Are much larger in plant cells.

Cells

Plant Cells Have two main differences from animal cells 1. Cell wall = a tough, usually flexible but sometimes fairly rigid layer that surrounds a cell 2. Chloroplasts = organelles found in plant and other eukaryotic organisms that conduct photosynthesis

Cell Wall - supports and protects PLANT cells (not found in animal cells) Cell Wall

Chloroplast - takes energy from the sun and makes food for the PLANT cell (not found in Animal Cells) Chloroplast

Cell Reproduction All organisms REPRODUCE. Why? –This allows for growth, development and the survival of the species

Gamete – The male or female reproductive cell that contains half of the DNA Egg Cell – The Ovum; the female reproductive cell (gamete); usually not mobile Sperm – The male reproductive cell (gamete) ; usually mobile

There are 2 types of reproduction 1.Asexual Reproduction –Requires A single parent!!! (sorry, just ONE).

Asexual Reproduction (cont)… Results in the offspring having the same hereditary material (DNA)

In other words, the new cells are an exact copy of its parent (allow for little variation among species) Asexual Reproduction (cont)…

Types of Asexual Reproduction Fission – cell splits in half (ex: Amoeba)

Types of Asexual Reproduction (cont)… Budding – a new organism grows off from the side of an adult (ex: Hydra)

Types of Asexual Reproduction (cont)… Regeneration – a new organism grows from a severed body part (ex: starfish)

The structure of a chromosome Chromosome Centromere Chromatid arm Gene

How do we replace old cells? Mitosis –The process in which the newly duplicated chromosome pairs are separated from each other

MITOSIS

Mitosis The process of cell division which results in the production of two daughter cells from a single parent cell. The daughter cells are identical to one another and to the original parent cell.

Mitosis can be divided into stages Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

Interphase The cell prepares for division Animal Cell –DNA replicated –Organelles replicated –Cell increases in size Plant Cell –DNA replicated –Organelles replicated –Cell increases in size

Interphase Animal Cell Plant Cell Photographs from:

Prophase The cell prepares for nuclear division Animal Cell –Packages DNA into chromosomes Plant cell –Packages DNA into chromosomes

Prophase Animal Cell Plant Cell Photographs from:

Metaphase The cell prepares chromosomes for division Animal Cell –Chromosomes line up at the center of the cell –Spindle fibers attach from daughter cells to chromosomes at the centromere Plant Cell –Chromosomes line up at the center of the cell –Spindle fibers attach from daughter cells to chromosomes at the centromere

Metaphase Animal Cell Plant Cell Photographs from:

Anaphase The chromosomes divide Animal Cell –Spindle fibers pull chromosomes apart –½ of each chromosome (called chromotid) moves to each daughter cell Plant Cell –Spindle fibers pull chromosomes apart –½ of each chromosome (called chromotid) moves to each daughter cell

Anaphase Animal Cell Plant Cell Photographs from:

Telophase The cytoplasm divides Animal Cell –DNA spreads out –2 nuclei form –Cell wall pinches in to form the 2 new daughter cells Plant Cell –DNA spreads out –2 nuclei form –New cell wall forms between to nuclei to form the 2 new daughter cells

Telophase Animal Cell Plant Cell Photographs from:

What happens to a cell after Mitosis is complete? Cytokinesis –Cell splits into two identical daughter cells with complete set of organelles

Mitosis Animation

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

How did you get here? Sexual Reproduction –Reproduction in which two (2) parents are involved –Sex cells are called gametes (egg and sperm cells are gametes)

What is sexual reproduction? Sexual reproduction – starts with the formation of gametes and ends when one gamete joins another gamete. The joining of egg and sperm is called fertilization, resulting in the production of a zygote zygote

How are gametes produced? Meiosis –A process whose purpose is to reduce the chromosome number in the cells –Produces 4 new cells with half the number of chromosomes as the parent

Parent Cell 1 st Division Meiosis – two divisions of the nucleus 2 nd Division – 4 new daughter cells with ½ the # of chromosomes

Meiosis continued Diploid Cells: have two of every chromosome (body cells) Haploid Cells: have just one chromosome from each pair (gametes)

MEIOSIS

Meiosis Meiosis is the type of cell division by which germ cells (eggs and sperm) are produced. One parent cell produces four daughter cells. Daughter cells have half the number of chromosomes found in the original parent cell

Meiosis During meiosis, DNA replicates once, but the nucleus divides twice.

Meiosis Four stages can be described for each division of the nucleus.

Meiosis I First division of meiosis

First Division of Meiosis Prophase 1: Each chromosome duplicates and remains closely associated. These are called sister chromatids. Metaphase 1: Chromosomes align at the center of the cell. Anaphase 1: Chromosome pairs separate with sister chromatids remaining together. Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the chromosome pair.

Prophase I

Prophase I

Metaphase I

Telophase I

Meiosis Second Division of Meiosis

Prophase 2: DNA does not replicate. Metaphase 2: Chromosomes line up at the center of the cell Anaphase 2: Centromeres divide and sister chromatids move separately to each pole. Telophase 2: Cell division is complete. Four haploid daughter cells are formed.

Prophase II

Metaphase II

Telophase II

Meiosis

Meiosis Animation

Differences in Mitosis & Meiosis Mitosis –Asexual –Cell divides once –Two daughter cells –Genetic information is identical Meiosis –Sexual –Cell divides twice –Four haploid daughter cells –Genetic information is different

Comparison Animations etics/sciber/animatin.htm

Cells (basic unit of life) Tissues (A group of cells performing a similar function) Organs (A group of tissues performing a similar function) Organ System (A group of organs performing a similar function) Organism An individual living thing made up of smaller parts that work together (You and Me)