Cell Growth, Division and Reproduction B1
B1. Basic Biological Principles 1. Describe the events that occur during 3 stages of the cell cycle: interphase, nuclear division, cytokinesis. 2. Compare and contrast processes and outcomes of mitosis and meiosis. 3. Explain how genetic information is inherited. 4. Explain the functional relationships between DNA, genes, alleles and chromosomes and their roles in inheritance.
B1. Vocabulary Allele genetics Allele frequency inheritance Cell cycle meiosis Chromosomes mitosis Crossing over nondisjunction Cytokinesis nucleus Deoxyribonucleic acid (DNA) DNA replication Gene gamete
Cell Size 1. Information Overload Large cells place more demands on the DNA to provide what the cell needs to live ANALOGY: What would happen to a growing town if it continued to grow?
Cell Size 2. Exchanging Materials Cells rely on movement of material across the cell membrane Large cells have trouble moving enough nutrients in and wastes out ANALOGY: Traffic Problems
ANALOGY: Lots of Growth can mean lots of trouble both in a town and in a cell Cell Size
Cell Size A process by which a cell divides into two new cells Solves the problem of overloading DNA and not being able to get enough materials in or out
Model it How does the surface area of a cube change as its volume increases? How does the relationship support the information learned today.
The Process of Cell Division Cells store information in DNA DNA is packaged into chromosomes Prokaryotes = single circular chromosome Eukaryotes = many chromosomes Chromatin = all of the chromosomes in the nucleus
The Process of Cell Division DNA is copied before cell division (replication) When a cell is not dividing, DNA is uncoiled (chromatin) During division, DNA coils up (condenses) and individual chromosomes can be seen
Which is easier to separate? Chromosomes during cell division Chromosomes before cell division
The Process of Cell Division Once replicated, each chromosome consists of two identical sister chromatids held together at the centromere
The Process of Cell Division The series of events a cell goes through as it grows and divides growth DNA replication Cell division End Result = two new daughter cells genetically identical to the parent cell
The Process of Cell Division happens quickly begins when the cell reaches a certain size is a form of asexual reproduction results in a new organism being formed called binary fission
The Process of Cell Division Multiple stages with checkpoints 1. Interphase a) G1: Cell Growth b) S: DNA Replication c) G2: Preparation for division 2. Cell division (also called M phase) a) Mitosis: division of the nucleus i. Prophase ii. Metaphase iii. Anaphase iv. Telophase b) Cytokinesis: division of the cytoplasm
The Process of Cell Division
The Process of Cell Division PROPHASE First phase of mitosis Chromosomes are visible Nucleus disintegrates Spindle fibers form Centrioles migrate
The Process of Cell Division METAPHASE Second phase of mitosis Chromosomes line up across the center of the cell
The Process of Cell Division ANAPHASE Third phase of mitosis Sister chromatids separate and move to opposite sides of the cell
The Process of Cell Division TELOPHASE Final phase of mitosis Chromosomes unwind Nucleus reforms around each new set of chromosomes Spindles break down
Take a Break QUICK CHECK CLICK HERE
Cell Division and Reproduction Cell division that results in a new organism Reproduction by a single parent Offspring are clones of parent Advantages: Quick - organisms well suited for an environment can reproduce very quickly Disadvantages: Lack of genetic diversity
Cell Division and Reproduction Results from the joining of two different cells Offspring have a mix of DNA from both parents Advantages: Offspring are genetically different Disadvantages: Slow takes time to mature and find a mate
Think about this How many chromosomes do you have in your cells? How many of those chromosomes came from dad? How many of those chromosomes came from mom?
Cell Division and Reproduction Homologous chromosomes = chromosomes that carry the same types of genes An organism with two parents must receive a set of genes from each parent Reproductive cells therefore can only carry a half of the chromosomes When an organism produces reproductive cells (sperm and egg), homologous chromosomes must separate Meiosis is the process that ensures the separation of homologous chromosomes
Cell Division and Reproduction
Cell Division and Reproduction Cell division that produces reproductive cells Begins with interphase (DNA replicated) Two rounds of division Meiosis I homologous chromosomes Meiosis II sister chromatids Each round of division consists of prophase, metaphase, anaphase and telophase
Cell Division and Reproduction End result of meiosis is different from mitosis 4 cells produced Each cell contains half the # of chromosomes that are needed in the organism (haploid) Cells that form are genetically different
Cell Division and Reproduction Begins with interphase (DNA replicated) Two rounds of division Meiosis I homologous chromosomes Meiosis II sister chromatids Each round of division consists of prophase, metaphase, anaphase and telophase
Cell Division and Reproduction Prophase I Homologous chromosomes pair up Crossing over occurs between homologous chromosomes (exchange of genetic info) Produces new combinations of genes
Keystone Prep Questions 1. Which statement best describes the phase of the cell cycle shown? A. The cell is in prophase of mitosis because the number of chromosomes has doubled. B. The cell is in prophase I of meiosis because the number of chromosomes has doubles. C. The cell is in telophase of mitosis because the cell is separating and contains two copies of each chromosome. D. The cell is in telophase of meiosis because the cell is separating and contains two copies of each chromosomes
Keystone Prep Questions 2. Mitosis and Meiosis are processes by which animal and plant cells divide. Which statement best describes a difference between mitosis and meiosis? A. Meiosis is a multi-step process. B. Mitosis occurs only in eukaryotic cells. C. Meiosis is used in the repair of an organism. D. Mitosis produces genetically identical daughter cells.