cell+reproduction

Cell Growth and Reproduction

Austin WoodJimena Pozo

Kirsten HermanSchyler RayTiara Fripp


• Cell Theory: – All cells come from pre-existing cells

• Cell Division:– Cells produced from one cell (parent cell)– Result is two or more identical cells– Repairs worn-out tissue (ex: skin) – Allows organisms to grow and change

• Ivy to wrap around a trellis


• Chromatin: long strands of DNA wrapped around proteins– Chromosomes exist as chromatin for most of

cell’s lifetime– Spaghetti noodles

• Chromosomes carry genetic information that is copied and passed on to new cells– Like wound spaghetti


Chromosome

Chromatin


• Before cell division, chromosome is in spaghetti-like CHROMATIN state

• As cell division begins, chromosomes take on a new tightly packed shape


• Cell Cycle: Sequence of growth and division of the cell.

• Majority of cell’s life is spent during INTERPHASE or the cell’s growth period


• INTERPHASE:– Longest phase: Growth Phase– Cell grows in size– Carries on metabolism– Chromosomes are duplicated to prepare for

division

• 3 Stages:


• INTERPHASE:– 3 Stages:

• Cell grows, protein production is high• Cell copies its chromosomes• Centrioles replicate and cell prepares for division


• After INTERPHASE, cell enters period of division, also called MITOSIS

• Mitosis: period of cell division– Forms two daughter cells with complete set of

chromosomes

Mitosis


• MITOSIS:– As cell gets to the maximum size, it begins to

undergo MITOSIS (cell division)

– FOUR PHASES:• Prophase• Metaphase• Anaphase• Telophase


• 1st Phase of Mitosis: PROPHASE– Long stringy chromatin coils up into visible

chromosomes

Spindle fibers

Disappearing nuclear envelope

Doubled chromosome


• 1st Phase of Mitosis: PROPHASE– Each duplicated chromosome is made of two

halves called SISTER CHROMATIDS

Sister chromatids


• 1st Phase of Mitosis: PROPHASE– Towards end of Prophase, nucleus begins to

disappear as nuclear envelope and nucleolus disintegrate

– Centrioles begin to migrate to opposite ends of cells


• 1st Phase of Mitosis: PROPHASE– Sister chromatids held together by

CENTROMERE• Located just outside of nucleus• Plays role in chromatid separation

Centromere


• 1st Phase of Mitosis: PROPHASE– As pairs of CENTRIOLES move to opposite

ends of cell, the SPINDLE forms between them• SPINDLE: football-shaped, cage-like structure• Separates sister chromatids during Mitosis

Spindle


• PROPHASE: Let’s break it down– Chromosomes coil up– Sister Chromatids form– Nucleolus and Nuclear Envelope disintegrates– Centrioles migrate to opposite ends– Spindles form between Centrioles


• 2nd Phase of Mitosis: METAPHASE– Doubled chromosomes attach to spindle fibers

by centromeres– Chromosomes pulled up by spindle fibers and

begin to line up on equator of spindles


• 2nd Phase of Mitosis: METAPHASE– One sister chromatid’s spindle fiber extends to

one pole while other spindle fiber extends to opposite pole


• 2nd Phase of Mitosis: METAPHASE– What is the importance?

• This arrangement of the chromatids ensures that each new cell receives identical and complete set of chromosomes (DNA)


• 3rd Phase of Mitosis: ANAPHASE– Beginning of sister chromatid separation– Centromeres split– Chromosomes separate from each other– Shortening of spindle fibers pull apart

chromatids to opposite poles


• 4th Phase of Mitosis: TELOPHASE– Begins once chromatids reach opposite poles– Chromosomes begin to to unwind– Spindle breaks down


• 4th Phase of Mitosis: TELOPHASE– Nucleolus and nuclear envelope reappears around

new set of chromosomes– Double membrane forms between two new nuclei– Two daughter cells formed


• Cytokinesis:– After Telophase, cell’s cytoplasm divides– Animal Cells: At end of Telophase, plasma

membrane pinches off forming two separate cells.

– Plant Cells: Cell plate laid across cell’s equator—there is no pinching off. Cell membrane forms around each cell and new cell walls form on each side of cell plate


• Cytokinesis:


• What are the results of Mitosis?– Single Cell organism remains a single cell but

has replicated itself– Multicellular organisms have grown or created

another cell that will work together as tissue to perform a certain function

cell+reproduction

Documents

Transcript of cell+reproduction