Cell Growth, Division and Reproduction

Transcription

1 Cell Growth, Division and Reproduction B1

2 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.

3 B1. Vocabulary Allele genetics Allele frequency inheritance Cell cycle meiosis Chromosomes mitosis Crossing over nondisjunction Cytokinesis nucleus Deoxyribonucleic acid (DNA) DNA replication Gene gamete

4 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?

5 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

6 ANALOGY: Lots of Growth can mean lots of trouble both in a town and in a cell Cell Size

7 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

8 Model it How does the surface area of a cube change as its volume increases? How does the relationship support the information learned today.

9

10 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

11 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

12 Which is easier to separate? Chromosomes during cell division Chromosomes before cell division

13 The Process of Cell Division Once replicated, each chromosome consists of two identical sister chromatids held together at the centromere

14 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

15 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

16 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

17 The Process of Cell Division

18 The Process of Cell Division PROPHASE First phase of mitosis Chromosomes are visible Nucleus disintegrates Spindle fibers form Centrioles migrate

19 The Process of Cell Division METAPHASE Second phase of mitosis Chromosomes line up across the center of the cell

20 The Process of Cell Division ANAPHASE Third phase of mitosis Sister chromatids separate and move to opposite sides of the cell

21 The Process of Cell Division TELOPHASE Final phase of mitosis Chromosomes unwind Nucleus reforms around each new set of chromosomes Spindles break down

22 Take a Break QUICK CHECK CLICK HERE

23 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

24 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

25 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?

26 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

27 Cell Division and Reproduction

28 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

29 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

30 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

31 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

32

33 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

34 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.