1 Pre-Test Directions: Answer each question TRUE OR FALSE. 1. Cells in the bodies of multicelled creatures, such as humans, are reproduced in a way that is very similar to the method used by most protozoa. 2. All human cells have two complete sets of chromosomes. 3. In biology, fertilization is when one cell divides into two cells. 4. Inside of cells, nearly all the genes are located on special structures known as microtubules. 5. Cell growth takes place during the stage of a cell's life cycle known as interphase. 2001 Ancient Lights Educational Media Published and Distributed by United Learning
2 Vocabulary List and Activity anaphase - The third stage of mitosis. During anaphase, the sister chromatids split apart at the centromere to become two separate chromosomes. Then the new chromosomes move toward opposite ends of the cell as the spindle microtubules shorten. asexual reproduction - A type of reproduction common in monerans and protists in which offspring are formed from only one parent organism. cancer cells - Cells that lose the ability to control how fast they reproduce. cell division - The process that results in two cells being formed from one cell. gene - A region of a DNA molecule that stores the instructions for making a particular protein. Genes are also known as the units of heredity. germ cells - The diploid reproductive cells that undergo meiosis to produce haploid sex cells. haploid - Having only one set of chromosomes. Sex cells, the sperm, and egg are haploid. Haploid cells are created in the reproductive organs by meiosis. heredity - Characteristics that are passed on from parents to their offsring. Genes are called the "units of heredity." hereditary - Passed on from one generation to the next. centrioles - Structures found in pairs in animal cells during mitosis around which the spindle develops. centromere- The place where the sister chromatids attach and the place where spindle microtubules attach to the chromosome. chromatin - Chromatin is the tangled, threadlike coils of chromosomes found in interphase cells. Chromatin contains DNA plus certain proteins. chromosomes - Chromosomes are worm-shaped structures that develop from chromatin before cells divide. Chromosomes contain DNAand protein. Human body cells have 23 chromosome pairs. cytoplasm - All the protoplasm located outside the nucleus. cytokinesis - The division of the cytoplasm that follows mitosis. Cytokinesis is caused by a "pinching off" of the cell membrane. diploid - Having two complete sets of chromosomes. This is the normal number of chromosomes found in the body cells of organisms that sexually reproduce. DNA replication - The duplication of the DNA. DNA replicates during the interphase stage of the cell cycle. fertilization - The union of female and male sex cells such as sperm and eggs. As a result of fertilization a zygote is formed. Through repeated cell re p roduction and new organism develops from the zygote. gamete - Another name for a sex cell. homolgous chromosomes - In diploid cells, these are the matching chromosomes. Human cells have a total of 46 chromosomes: 23 pairs of homologous chromosomes. interphase - Ninety percent of a normal cell's life cycle is spent in interphase. During interphase, the cell makes specialized cell products, its DNA replicates, its centrioles divide (if it is an animal cell), and new organelles are made. Chromosomes are not visible during interphase. nuclear - Refers to the nucleus. nucleus - (Plural: nuclei) Arounded structure located in the cytoplasm. The nucleus is the cell's control center because it is where most of the DNA is located. nucleolus - "Little Nucleus" The area of the nucleus where ribosomes are made. Cells can have more than one nucleolus. During prophase the nucleolus disappears. meiosis - The process that takes place in reproductive organs such as the ovaries and testes whereby haploid sex cells are created from diploid germ cells. This occurs because the DNA replicates only once but the cells divide twice. Meiosis is sometimes called reduction division. metaphase - The second stage of mitosis during which the duplicated chromosomes line up in the center (equator) of the mitotic spindle. mitosis - The part of a cell's life cycle when its nucleus is duplicated. (Continued on Blackline Master 3) 2001 Ancient Lights Educational Media Published and Distributed by United Learning
3 mitotic spindle - Also, just spindle. A system of microtubules that appears during mitosis. The spindle microtubules act to separate the chromosomes. ovum - (Plural ova) An egg. A female sex cell. Ova are haploid cells produced in the ovaries by meiosis. ovary - The main organ of the female reproductive system where ova are formed. polar bodies - The three small structures, little more than haploid nuclei, that along with a single ovum are produced during meiosis in humans. Polar bodies serve no reproductive function. Vocabulary List and Activity (continued) telophase - The final stage of mitosis. During telophase daughter nuclei form as the chromosomes change back into chromatin and new nuclear membranes develop. The division of the cytoplasm, cytokinesis, is usually well underway by telophase. testis - Plural testes. The male reproductive organ which produces sperm and male sex hormones. X chromosome - One of the two human sex chromosomes. These chromosomes carry the genes that determine the sex of the offspring. If a pair of X chromosomes is present the offspring will be female. prophase - The first stage of mitosis. During prophase the chromosomes make their appearance from chromatin and the spindle forms as the nuclear membrane breaks down. During prophase the chromosomes are actually doubled and are made up of two identical strands called sister chromatids. reduction division - Another term for meiosis. sex cells - Also called gametes: the sperm and eggs. The haploid male and female cells produced during meiosis that join during fertilization to create the single diploid cell called a fertilized egg (zygote). sexual reproduction - Reproduction that involves the production and fusion of male and female sex cells to form a diploid fertilized egg. sister chromatids - The two parts of a duplicated chromosome that are present in prophase and metaphase. The sister chromatids are pulled apart during anaphase to become independent chromosomes. sperm - The male sex cells. These haploid cells are created in the testes during meiosis. Vocabulary Activity From the vocabulary list, find the appropriate word to fill in the blank. 1. During the stage of mitosis called, the chromosomes develop from chromatin. 2. During meiosis, the chromosome number is reduced by. 3. Aging may be explained by the existence of chromosome structures of DNA called. 4. Only one parent is needed for reproduction. 5. In human females, only one egg is produced during meiosis plus three, which are little more than haploid nuclei that serve no reproductive function. spindle - Same as mitotic spindle. spindle microtubules - (Also called spindle fibers) The microtubular structures that form the mitotic spindle. telomeres - DNA structures that have been described as being like the plastic tips on shoelaces: They keep they DNA from unravelling. Everytime a cell divides part of each telomer on each chromosome is destroyed. This process is believed to be related to the aging of cells. 2001 Ancient Lights Educational Media Published and Distributed by United Learning
4 1 3 Crossword Puzzle 1 5 2 2 3 4 6 4 5 ACROSS: 1. Having only one set of chromosomes is called the condition of the cell. 2. The process of duplicating the nucleus is called. 3. A is a fertilized egg. 4. In normal cell reproduction the stage right before the daughter cells are formed is called. 5. Having two complete sets of chromosomes is called the condition of the cell. 6. The period of a cell's life cycle when its DNA is replicated is called. DOWN: 1. After the nucleus has been duplicated, the cytoplasm divides. This process is called. 2. Cells used for sexual reproduction are formed by a process called. 3. The chromosomes seen in prophase are made up of two sister. 4. During metaphase the duplicated chromosomes are lined up on the equator of the. 5. Cells that have lost the ability to control the rate at which they reproduce are called cells. 2001 Ancient Lights Educational Media Published and Distributed by United Learning
5 Post-Test Directions: Describe the things that occur during each of the following: 1. Prophase of mitosis 2. Interphase 3. Metaphase of mitosis 4. Anaphase of mitosis 5. Cytokinesis 6. Fertilization 2001 Ancient Lights Educational Media Published and Distributed by United Learning
6 Video Quiz Directions: Answer the following questions TRUE OR FALSE. 1. TRUE OR FALSE? Diploid cells have two full sets of chromosomes. 2. TRUE OR FALSE? DNA replication takes place during the metaphase stage of mitosis. 3. TRUE OR FALSE? Chromosomes are not visible during most of a cell's life cycle. 4. TRUE OR FALSE? Asexual reproduction requires only one parent. 5. TRUE OR FALSE? Meiosis does not occur in most types of cells. 2001 Ancient Lights Educational Media Published and Distributed by United Learning