AIM: Why and how do cells divide. DN: Compare and Contrast Sexual and Asexual Reproduction. HW: Castle Learning due Monday

Compare the size of these organisms Vs.

Do these organisms have different size cells? No How do organisms get so big? Cell Division

Why do cells divide rather than grow in size? XX +

DNA “Overload” DNA Library Small Town City Nucleus (DNA) loses control over the Cell as it grows larger!!

Exchange of Materials Cell Membrane 4 small cells have more surface area than 1 big cell More cell membrane – less cytoplasm Surface area Rate of Exchange Increases

Surface Area Small particles have a relatively larger surface area than large particles. What will melt first? Ice Cube Ice Chips Vs. Why? The smaller chips have more surface area. Smaller cells have more surface area and can exchange materials across membrane more efficiently.

What is Cell Division? One cell divides into 2 new daughter cells Size?

What happens to the chromosomes before a cell divides? They need to replicate What does replication mean? To make an exact copy of the chromosome.

Chromosomes Replicate before the cell divides 1 Chromosome 2 Chromatids Centromere

When do cells divide? Organism Growth

When do cells divide? Repair

What tissues in our body need to undergo a lot of cell division? Skin Stomach Bone Why? y ?

What is Mitosis? Mitosis is the process that divides the cell’s nucleus into two, each with a complete set of genetic material from the parent’s cell

What are the phases of the Cell Cycle? Centriole Interphase

Stages of Mitosis: Prophase: 1)The chromosomes becomevi sible. 2)The centrioles separate and Spindle fibers begin to form. 3)The nuclear membrane breaks down. Centriole Spindle Fibers Nuclear Membrane

Stages of Mitosis: Metaphase: 1)The chromosomes line up across the center of the cell. 2)Each chromosome is connected to a spindle fiber at the centromere.

Stages of Mitosis: Anaphase: 1)The spindle fibers separate the chromatids into individual chromosomes and are they are moved apart.

Stages of Mitosis: Telophase: 1)The chromosomes gather at opposite ends of the cell. 2) Two new nuclear membranes form. 3)The chromosomes lose their distinct shapes.

Cytokinesis: The cytoplasm pinches and two cells are formed.

What is the end result of Mitosis? 46X + Chromosome Number? ParentDaughter Cell Is the genetic material of the daughter cells identical to the parent? The same number of chromosomes is maintained from one generation to the next. YES

Mitosis Phases Prophase MetaphaseAnaphase Telophase Cytokinesis

Plant Cells vs. Animal Cells Which are plant cells and which are animal cells? Cell Wall Animal Cells Plant Cells

Plant Cell vs. Animal Cell Mitosis In plants, a Cell Plate forms across the middle of the cell. In an animal cell, the cytoplasm pinches off. What process is this? Cytokinesis How is plant cytokinesis different than animal cell cytokinesis?

Which phase are these cells in? Prophase Anaphase

What phase are these cells in? Metaphase Telophase