Chapter 6 Chromosomes and Cell Reproduction I Chromosomes
- Slides: 35
Chapter 6 - Chromosomes and Cell Reproduction
I. Chromosomes
A. New cells are formed by cell division. 1. An adult human body produces about 2 trillion cells EVERY day! This is about 25 million new cells per second! l 2. l 3. Eukaryotic organisms undergoing growth, development, repair, or asexual reproduction divide by a different type of cell division. Cell division allows for this.
Continued l 4. Gametes are reproductive cells (egg and sperm) undergo meiosis for cellular division.
B. Bacterial cells divide to reproduce 1. Bacteria reproduce by a type of cell division called binary fission. l 2. Binary fission is a form of asexual reproduction that produces identical offspring. 3. In asexual reproduction a single parent passes exact copies of its entire DNA to its offspring.
C. Eukaryotic cells form chromosomes before cell division l 1. A gene is a segment of DNA that codes for a protein or RNA molecule. 2. As a Eukaryotic cell prepares to divide, the DNA and the proteins associated with DNA coil into a structure called chromosomes.
Continued l 3. Chromosomes are squished together called chromatids. 4. The chromosome has two strands – one from mom and one from dad. A “twist tie” called a centromere holds them together. See page 119.
Centromere
D. Chromosome number and structure affect development. l 1. Each human somatic (any cell besides sex cells) normally contain two copies of 23 chromosomes for a total of 46 chromosomes. l 2. Each chromosome contains thousands of genes that play important roles in determining how a person’s body develops and functions.
Continued l 3. Each of the 23 pairs of chromosomes consists of two homologous chromosomes. l 4. Homologous chromosomes are chromosomes that are similar in size, shape and genetic content.
Continued l 5. All of the cells in the body, besides gametes have two pairs of chromosomes. (One from mom one from dad) they are called diploid. l 6. Sex cells only have DO NOT have a pair, they are called haploid (1/2 the amount of chromosomes)
Continued 7. A zygote is a fertilized egg cell. l 8. Look at figure 6 -1 pages 121 to view number of chromosomes.
E. Chromosomes determine your sex. l 1. Of the 23 pairs of chromosomes in human somatic cells, 22 pairs are called autosomes l 2. Autosomes are chromosomes that are not directly involved in determining the sex of an individual. l 3. The sex chromosomes, one of the 23 pairs contain the gene that determines the gender. Males determine the gender of the human.
F. Change in chromosome number l 1. Sometimes a human could have different chromosome numbers. l 2. A karyotype is performed to view an individual’s chromosomes. l 3. Down syndrome is an extra copy on pair 21.
II. The cell Cycle A. The cell cycle describes the life of a Eukaryotic cell. l 1. The cell cycle is a repeating sequence of cellular growth and division during the life of an organism. l 2. A cell spends 90% of its time in the first three phases of the cycle-interphase.
Continued l 3. First growth (G 1)phase- a cell grows rapidly and carries out its routine functions. Cells that are not dividing remain in the G 1 phase. 4. Synthesis (S) phase- A cell’s DNA is copied during this phase. At the end of this phase, each chromosome consists of two chromatids attached at the centromere.
Contined l 5. Second growth (G 2) phase-In the G 2 phase, preparations are made for the nucleus to divide. 6. Mitosis-the process during cell division in which the nucleus of a cell is divided into two nuclei.
Continued l 7. Each nucleus ends up with the same number and kinds of chromosomes as the original cell. 8. Cytokinesis-the cytoplasm splits.
B. The cell cylce is carefully controlled l 1. If a cell spends 90% of its time in interphase how do cells “know” when to divide? l 2. Cell Growth (G 1) checkpoint-This checkpoint makes the key decision of weather the cell will divide or not.
Continued l 3. DNA synthesis (G 2) checkpoint-DNA replication is checked at this point by DNA repair enzymes. If this checkpoint is passed, proteins help to trigger mitosis. l 4. Mitosis checkpoint-will trigger the exit from mitosis.
C. When control is lost: cancer l 1. Certain genes contain the information necessary to make the proteins that regulate cell growth and division. l 2. If one of these genes is mutated, the protein may not function.
Continued l 3. Cancer is the uncontrolled growth of cells. l 4. Cancer is a disorder of cell division.
D. Mitosis l I Prefer Mangos And Tangerines Interphase (not really a phase) Prophase Metaphase Anaphase Telophase Cytokinesis
INTERPHASE l Interphase- is part of the cell cycle before mitosis. During Interphase The cell grows – DNA is being copied – This period between cell division can be very long. –
INTERPHASE
PROPHASE l Prophase- This is the longest phase. During this phase; l l The nuclear envelope disappears. The centrioles start to move to the opposite poles. Spindle fibers start to form. Chromosomes are becoming evident.
PROPHASE
METAPHASE l Metaphase-Metaphase is the shortest phase of mitosis. l The chromosomes line up in the middle of the cell.
METAPHASE
ANAPHASE l ANAPHASE- Begins when the centromere that join the sister chromatids start to split. l The chromosomes are being pulled to the opposite sides of the cell toward the Centrioles.
ANAPHASE
TELOPHASE l TELOPHASE-Final process of mitosis. l l Chromosomes are at the opposite poles. Nuclear envelope reforms.
TELOPHASE
CYTOKINESIS-Splitting of the cytoplasm.
Teacher note: http: //www. cellsalive. com/mitosis. htm
- Chapter 6 chromosomes and cell reproduction
- Sexual reproduction and asexual reproduction
- Asexual reproduction cell division
- Sexual asexual venn diagram
- Cell growth division and reproduction
- The scientist mathias schleiden studied _______ in ______.
- Cell reproduction
- Is mitosis asexual
- Cell of reproduction
- Cell reproduction
- A cell with four chromosomes going through meiosis
- Chromosome description and function
- Diploid vs haploid number
- What does mitosis make
- Pedigree miscarriage symbol
- Chapter 20 reproduction and pregnancy
- Chapter 10 sexual reproduction and genetics
- Chapter 34 reproduction and development answer key
- Advantages of diaphragm cell
- Linear chromosomes in eukaryotes
- Animal and plant cell venn diagram
- Tonoplast
- Rough endoplasmic reticulum function
- Primary battery and secondary battery
- Differences between plant animal and bacterial cells
- Section 10-2 cell division
- Prokaryotic cell and eukaryotic cell
- Idealized plant cell
- Walker cell and hadley cell
- Cell cycle and cell division
- Plant cell animal cell venn diagram
- Cell cycle phases
- Electrolytic cell picture
- What is the gooey liquid in plant and animal cells
- Chapter 20 sexual reproduction in animals
- Chapter 21 human reproduction answer key