Why is cell size limited? How does the surface area to volume ratio affect a cell? The larger the surface area to volume ratio, the more efficiently the cell can get nutrients Why is cell size limited? If cells get too big, their volume increases faster than surface area; the cell can’t get nutrients in and wastes out fast enough If cells are too small, the organelles can’t fit and function correctly What are the two major phases of the cell cycle? Interphase and M-phase

G1, S, and G2 What are the 3 phases of Interphase? What happens during G1 of Interphase? normal growth and functioning; organelles are copied What happens during S of Interphase? DNA is replicated (copied)

Mitosis and Cytokinesis What happens during G2 of Interphase? normal growth and functioning Why is replication of DNA and the cell’s organelles important? When the cell divides, it will need to give each daughter cell all of the organelles and a full set of DNA What are the two major events that occur during the M-phase? Mitosis and Cytokinesis

Cell Division What occurs during the M-phase? What is mitotic cell division (mitosis and cytokinesis)? When a parent cell divides into two identical daughter cells What happens during mitosis? The parent cell DNA (in the nucleus) is organized and divided between the two new daughter cells (in two new nuclei)

How does cytokinesis occur in plant cells? What happens during cytokinesis? The cytoplasm of the parent cell is divided to create two daughter cells How does cytokinesis occur in plant cells? A cell plate grows between the two cells and forms a new cell wall on each side How does cytokinesis occur in animal cells? The cell membrane pinches inward to form a cleavage furrow until the two cells are pinched apart

They have a rigid cell wall. Why can’t plant cell membranes pinch inward during cytokinesis? They have a rigid cell wall. What is the purpose of mitosis in unicellular organisms? Asexual reproduction: one organism creates two new organisms What is the purpose of mitosis in multicellular organisms? Replace dying cells or help the organism grow

Mitosis occurs in what type of cells? Somatic (body) cells What is the most basic form of DNA? Double helix What are the building blocks (monomers) of DNA? nucleotides

Proteins called histones What does DNA wrap around to start condensing? Proteins called histones What is chromatin? DNA wrapped around histones and condensed into “spaghetti” form When chromatin coils up on itself into a supercoil, what is formed? Chromosomes

What is half a chromosome called? chromatid A chromosome that has its copy attached to it (from the S phase of Interphase) is made up of 2 what? Sister chromatids Sister chromatids are held together at the what? centromere

What form of DNA is present during Interphase? Chromatin What form of DNA is present during mitosis? chromosomes What is the role of spindle fibers during cell division? To help organize and separate the DNA

What do centrioles do during cell division? Organize the spindle fibers Why do cells divide at different rates? Some cells need to be replaced more often than other types of cells according to their function in the body What are the four phases of mitosis? Prophase Metaphase Anaphase Telophase

What happens during Prophase? The nucleolus and nuclear membrane “break up” and temporarily disappear. Chromatin has condensed into chromosomes, each consists of two identical sister chromatids Centrosomes and Centrioles migrate to opposite sides of the cell Spindle fibers grow from the centrioles and radiate toward the center of the cell. What happens during Metaphase? Spindle fibers attach to the chromosomes and help line the chromosomes up across the center of the cell on an imaginary line called the metaphase plate or cell equator The chromosomes line up across the center of the cell on an imaginary line called the metaphase plate. Microtubules attach to the centromere of each chromosome from both poles of the spindle.

Interphase What happens during Anaphase? Spindle fibers shorten, breaking sister chromatids apart to form separate chromosomes. The chromosomes are pulled to opposite ends of the cell What happens during Telophase? Chromosomes begin to unwind back to chromatin. The nuclear envelope and nucleolus reappear in each daughter cell The spindle disappears What is this phase? Interphase

What is this phase? Prophase Metaphase Anaphase

What is this phase? Telophase