Materials move through cells by diffusion Oxygen and

Materials move through cells by diffusion. Oxygen and food move into cells, while waste products move out of cells. How does the size of a cell affect how efficiently materials get to all parts of a cell? Work with a partner to complete this activity 1. On a sheet of paper, make a drawing of a cell that has the following dimensions: 5 cm x 5 cm. Your partner should draw another cell about one half the size of your cell on a separate sheet of paper. 2. Compare your drawings. How much longer do you think it would take to get from the cell membrane to the center of the big cell than from the cell membrane to the center of the smaller cell? It would take twice the amount of time. 3. What is the advantage of cells being small? If cells are small, materials can be distributed to all parts of the cell quickly.

Image from: http: //www. bcps. org/offices/lis/models/life/images/grow. JPG CELL GROWTH & DIVISION 10 -1 & 10 -2 Image by Riedell

2 Reasons why cells divide DNA OVERLOAD 1. ___________ As cell grows bigger demand on DNA “genetic library” becomes too great Ex: Small town library has 1000 books. As town grows and more people borrow books, there may be a waiting list to read the most popular titles http: //www. adc. state. az. us/images/Off-Library. JPG

2 Reasons why cells divide Material exchange can’t keep up 2. ___________ As cell grows bigger demand for transport across membrane is too great http: //www. animationlibrary. com

Ability to transport of oxygen, food, waste across cell membrane depends on ________ SURFACE AREA Need for these depends on CELL VOLUME ______ As cell grows these DON’T increase at the same rate See relationship between volume and SA

Ratio of Surface Area to Volume in Cells Section 10 -1 Cell Size Surface Area (length x width x 6) Volume (length x width x height) Ratio of Surface Area to Volume Go to Section:

BIGGER CELLS NEED MORE FOOD and OXYGEN, but CAN’T TRANSPORT IT FAST ENOUGH or IN BIG ENOUGH QUANTITIES! http: //www. animationlibrary. com

Image from: http: //www. bcps. org/offices/lis/models/life/images/grow. JPG Image by Riedell Multicellular organisms grow mainly by increasing cell number

DNA CAN BE: SPREAD OUT IN NON-DIVIDING CELLS CHROMATIN SCRUNCHED UP IN DIVIDING CELLS CHROMOSOMES

DNA in PROKARYOTES • BACTERIAL DNA is CIRCULAR • HAVE ONE CHROMOSOME • NO NUCLEUS; ATTACHED TO CELL MEMBRANE http: //www. origin-life. gr. jp/3202121/fig 6. jpg

DNA in EUKARYOTES (Plants & Animals) • DNA is ROD-SHAPED CHROMOSOMES • MANY PAIRS • FOUND IN NUCLEUS http: //cellbio. utmb. edu/cellbio/chrom 2. jpg

Chromosome structure CHROMATIDS • __________ 2 identical arms • _________ CENTROMERE constricted area holds chromatids together HOMOLOGOUS • _________ PAIR 2 of each chromosome (one from mom; one from dad)

HOMOLOGOUS CHROMOSOMES • SAME SIZE • SAME SHAPE • CARRY GENES for the SAME TRAITS IDENTICAL • BUT NOT _______! (Don’t have to have the SAME CHOICES) http: //arnica. csustan. edu/biol 3020/cell_division. htm http: //sps. k 12. ar. us/massengale/genetics%20 tutorial. htm

CELL DIVISION in PROKARYOTES Bacteria reproduce using BINARY FISSION _________________ http: //fig. cox. miami. edu/~cmallery/150/mitosis/fission. jpg

CELL CYCLE _______ = series of events that cells go through as they grow and develop cells alive cell cycle

CELL CYCLE INTERPHASE – non-dividing phase G 1 - Grow bigger Cell is “doing its job” DNA is spread out as chromatin S - Synthesis (copy DNA) & chromosomal proteins G 2 - Grow bigger, make organelles & molecules needed for cell division

CELL DIVISION MITOSIS – Nuclear division Prophase Metaphase Anaphase Telophase Cytokinesis – Cytoplasm divides G 0 – cell stops dividing (Ex: nerve cell)

Figure 10– 4 The Cell Cycle Section 10 -2 G 1 phase M phase S phase G 2 phase Go to Section:

INTERPHASE (G 1 - S - G 2) In between divisions Cells are in this phase most of the time Can see nucleus DNA spread out as chromatin Can’t see chromosomes DNA gets copied (S) Cell gets ready to divide

Pearson Education Inc publishing as Pearson Prentice Hall PROPHASE 1 st dividing phase http: //www. life. uiuc. edu/plantbio/102/lectures/08 mit&veg 102. html DNA scrunches into chromosomes Centrioles appear in centrosome region & move to poles Nuclear membrane & nucleolus disappear Spindle fibers form & attach to chromosomes

CENTROSOME ____ region organizes spindle Spindle MICROTUBULES are part of cytoskeleton http: //www. coleharbourhigh. ednet. ns. ca/library/organelle_worksheet. htm

METAPHASE Chromosomes line up in middle ______ Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http: //www. science. siu. edu/plant-biology/PLB 117/JPEGs%20 CD/0247. JPG

ANAPHASE Centromeres split apart Centrioles pull chromatids_______ Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http: //www. science. siu. edu/plant-biology/PLB 117/JPEGs%20 CD/0247. JPG

TELOPHASE (reverse prophase steps) two nuclei See ______ Nuclear membrane & nucleolus return Chromosomes spread out as chromatin Centrioles disappear Spindle fibers disappear Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http: //www 2. bc. ca. us/cnewton/Biology%2011/Mitosis. html

CYTOKINESIS Cytoplasm splits into 2 cells ANIMAL CELLS pinch cytoplasm in two with a ___________ CLEAVAGE FURROW

CYTOKINESIS Cytoplasm splits into 2 cells PLANT CELLS can’t pinch because they have a sturdy ______ CELL WALL Plant cells separate cytoplasm by CELL PLATE growing a ________ down the middle. http: //www. eastcentral. edu/acad/depts/BI/plant_mitosis_nolabels. html

Figure 10– 5 Mitosis and Cytokinesis Section 10 -2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Go to Section: Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase

Videos Animal Cell Mitosis Animal Cell Cytokinesis

Concept Map Section 10 -2 Cell Cycle includes is divided into Go to Section: is divided into

Concept Map Section 10 -2 Cell Cycle includes Interphase M phase (Mitosis) is divided into G 1 phase Go to Section: S phase G 2 phase Prophase Metaphase Anaphase Telophase

SOUTH DAKOTA CORE SCIENCE STANDARDS LIFE SCIENCE: Indicator 1: Understand the fundamental structures, functions, classifications, and mechanisms found in living things 9 -12. L. 1. 1. Students are able to relate cellular functions and processes to specialized structures within cells. • Transport (ANALYSIS) cell membranes, homeostasis • Cell life cycles (ANALYSIS) Examples: somatic cells (mitosis)

Core High School Life Science Performance Descriptors High school students performing at the ADVANCED level: predict the function of a given structure; predict the outcome of changes in the cell cycle; predict how homeostasis is maintained within living systems; High school students performing at the PROFICIENT level: describe the relationship between structure and function explain how homeostasis is maintained within living systems; compare and contrast the cell cycles in somatic and germ cells; High school students performing at the BASIC level recognize that different structures perform different functions define homeostasis; describe the life cycle of somatic cells;