Guided Notes: Cellular Reproduction When do cells divide? Cells grow and function normally until they become too. Cell size is because increases faster than This means that there is not enough area on the of the cell to bring in the amount of needed for the growing of the cell. Surface area must allow for adequate of materials. Otherwise, the cell would because it is unable to import and export needed. Why do cells divide? Three reasons: 1. 2. 3. Once a cell reaches its size limit, it either stops or it. 1
The Cell Cycle the series of that cells go through as they and. During the cell cycle, a cell: Before the cell can begin the phase of the cell cycle, the located within must be. Why is it important for DNA to Condense? Condensing makes it to DNA around in the. Kind of like packing a suitcase. It s easier to move your clothes from place to place if they are packed. Chromosomes at the start of mitosis: - DNA wraps around proteins called which are similar to beads on a string. - This forms, a combination of DNA and proteins. - The chromatin then condenses into small, thick rods of. 2
DNA Double Helix DNA and Histones Chromatin and DNA Supercoiled DNA Making Sense of DNA Terms: DNA is usually in the form of. Before the cell divides, DNA is duplicated to form. The holds the chromatids together. Then DNA organizes into. protect the ends of chromosomes and help prevent the of genes. The wearing away of telomeres is what causes us to age. 3
There are two types of cells, so there are two types of cell division: cells do Binary Fission: In cells, it s more complex. Cell division in eukaryotes is called Mitosis. Mitosis is part of the Cell Cycle. The Cell Cycle has three main stages (or phases): 1. - when cell grows and prepares to divide 2. - when nucleus divides 3. - when cytoplasm divides and two new cells are formed (called daughter cells). Interphase has three phases: - ( Growth 1 ) = proteins and organelles are made so cell can grow larger - (DNA Synthesis ) = DNA is replicated in preparation for cell division - ( Growth 2 ) = cell takes inventory of DNA and organelles to prepare for mitosis. Mitosis has four stages: PMAT or Please Make Another Taco P - DNA and proteins into tightly coiled ; The nuclear envelope ; begin to move to opposite poles; form M - spindle fibers attach to each chromosome at the ; Chromosomes line up in the of the cell. A - sister chromatids separate to of the cell; spindle fibers begin to which pulls sister chromatids away from each other towards opposites poles of the cell T - nuclear start to reform around each identical set of chromosomes; chromosomes begin to ; spindle fibers 4
Cytokinesis cyto = cytoplasm kinesis = divides Cytoplasm and cell contents divide Division of cell into two identical cells called Daughter cells have the same # of chromosomes as each other and as the parent cell from which they were formed. See animation Differs in animal and plant cells o In animal cells, the membrane pinches closed to form a cleavage furrow. o In plant cells, a forms between the two nuclei. What factors control cell division? Regulation of the Cell Cycle: Cell growth and division must be and regulated within the cell or serious problems can occur, like cancer. Factors that regulate cell division: 1. factors 2. factors 3. Internal Factors come from the cell and are triggered by external factors - proteins that kinases - are rapidly made and destroyed at certain points of the cell cycle External Factors come from the cell from nearby cells and parts of the body. External factors include physical and chemical signals: 1. to - once a cell touches other cells, it stops dividing. 5
2. - are that stimulate cell division - come from cells - cells grow and divide in response to a of different growth factors, not just 3. - may the growth of certain cell types Apoptosis cell death (cell suicide) - caused by a cell s production of self-destructive - it is a feature of healthy organisms - the will shrink and break apart, and cells from the system will gobble up the cell and its parts. Uses of apoptosis - embryonic and infant - cell death of cells Example: In early stages of development, human embryos have between fingers and toes. These cells typically go through apoptosis a baby is born. Cancer Basics - What is Cancer? Cancer is caused by changes in the that control normal and death. Cancer occurs when continue to grow and divide and die when they should. Cancer cells form disorganized clumps called. tumors remain clustered and can be removed. tumors metastasize, or, and can form more tumors elsewhere in the body. The changes that cause cancer may be, or may result from or lifestyle factors. - any substance known to produce or promote the development of cancer. Causes of Cancer: factors tobacco, chemicals, radiation, and infectious organisms factors inherited mutations, hormones, disease Treatments for Cancer, radiation, chemotherapy, hormones, and immunotherapy - used to kill cancer cells in a specific area/region - uses drugs to kill actively dividing cells (also kills healthy cells) 6