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122 Cards in this Set
- Front
- Back
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What does cell division do?
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increases the number of cells and causes many-celled
organisms to grow |
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What is the cell cycle?
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series of events that takes place from one cell division to the next
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Cells have periods of formation, growth and development, and death called ____ ______.
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life cycles
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Most of the life of any eukaryotic cell is spent in a period of growth and development is called what?
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interphase
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What is a eukaryotic cell?
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a cell with a nucleus
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During interphase, a cell duplicates its __________ and prepares for ____ ________.
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chromosomes; cell division
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After interphase, the _______ divides to form two identical ______.
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nucleus; nuclei
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What is mitosis?
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a process in which the nucleus divides to form two identical nuclei
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What is a chromosome?
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a structure in the nucleus that contains hereditary material
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What three things happen in prophase?
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1) Nucleolus and nuclear membrane disintegrate
2) Centrioles move to opposite ends of the cell 3) Spindle fibers begin to stretch across the cell |
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What happens during metaphase?
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pairs of chromatids line up across the center of the cell
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What two things happen during anaphase?
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1) Each centromere divides
2) Each pair of chromatids separates and moves to opposite ends of the cell |
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What is it called when spindle fibers disappear and a new nucleus forms?
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telophase
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What is the division of the cytoplasm?
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for most cells, the cytoplasm separates after the nucleus divides
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In the division of the cytoplasm, what happens in animal cells?
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the cell membrane pinches in the middle and the cytoplasm divides
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In the division of the cytoplasm, what happens in plant cells?
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a cell plate forms
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What is the result of mitosis?
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allows growth and replaces worn out or damaged cells
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Each cell in your body, except ___ _____, has a nucleus with __ chromosomes.
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sex cells; 46
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What is asexual reproduction?
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a new organism is produced from one parent organism
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An organism with no nucleus divides into two identical organisms by _______.
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fission
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What is budding?
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a small, exact copy of the adult grows from the body of the parent
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In ___________, a whole new organism grows from each piece of the parent.
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regeneration
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Why is cell division important?
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We wouldn't be able to grow or heal by replacing worn-our and damaged cells without cell division.
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What is sexual reproduction?
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two sex cells, usually an egg adn a sperm, come togther
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What is the joining of an egg and a sperm, generally from two different organisms of the same species?
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fertilization
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Where are sperm and eggs formed?
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-sperm=male reproductive organs
-eggs=female reproductive organs |
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What is a zygote?
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a cell that forms from fertilization
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Following fertilization, ____ ________ begins and a new organism develops.
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cell division
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What are human body cells? Diploid or haploid?
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diploid
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What arre diploid cells?
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cells that have 23 pairs of similar chromosomes
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What are haploid cells?
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cells that have 23 single chromosomes
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What are human sex cells? Diploid or haploid?
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haploid
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What is the process that produces haploid sex cells and ensures that offspring have the same diploid number as its parent?
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meiosis
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What happens in meiosis I?
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the nucleus divides adn produces two new cells with one duplicated chromosome each
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What happens in meiosis II?
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the nuclei divide and the chomatids separate, producing four cells with half the number of chromosomes of the original nucleus
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Why do you think sex cells must be haploid?
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A sex cell has 23 single chromosomes so that when it joins another sex cell, the two sets of single chromosomes can pair up and produce an organism with 46 chromosomes and unique traits.
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What is DNA?
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a chemical that contains information that an organism needs to grow and function
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What does DNA stand for?
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Deoxyribonucleic acid
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Who made an accurate modle of DNA in 1953?
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Watson and Crick
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What is the structure of DNA similar to?
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a twisted ladder
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The sides of the ladder (in DNA) are made up of _____-_________ molecules
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sugar-phosphate
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The rungs of the ladder (in DNA) are made up of ________ bases.
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nitrogen
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Before a cell divides, how does DNA duplicate itself?
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by unwinding and separating its sides, then each side becomes a pattern on which a new side forms
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What are genes?
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sections of DNA on a chromosome
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What do genes contain?
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instructions for making specific proteins
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What does RNA carry?
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the codes for making proteins from the nucleus to the ribosomes in the cytoplasm
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What are the three types of RNA and their jobs?
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1) Messenger RNA - carries the code that directs the order in which the amino acids bond
2) Ribosomal RNA - makes up ribosomes, where proteins are built 3) Transfer RNA - brings amino acids to the ribosomes to build the protein |
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Cells use only the _____ that direct the making of proteins needed by that cell.
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genes
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What are mutations?
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any permanent change in DNA sequence of a cell's gene or chromosome
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What can mutations be caused by?
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outside factors like X-rays, sunlight, and some chemicals
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A change in a gene or chromosome can change the ______ of an organism.
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traits
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How do you think cancer spreads?
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Something, such as sunlight, causes a mutation in the genes of one cell. When that cell's chromosomes copy themselves, the new chromosomes both have the mutation. When the cell divides, both new cells carry the same mutation. Those two cells divide into four cells that carry the mutation, and so on, causing the cancer to grow.
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What is heredity?
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the passing of traits from parent to offspring
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In heredity, what do genes on chromosomes control?
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the traits that show up in an organism
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The different forms of a trait that a gene may have are what?
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alleles
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During meiosis what happens to the pair of chromosomes and the alleles?
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a pair of chromosomes separates and the alleles move into separate sex cells
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What is the study of how traits are inherited?
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genetics
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Who is Gregor Mendel?
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the father of genetics
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Mendel was the first to use mathematics of probability to explain ________ and to trace one trait for several generations.
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heredity
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What does a hybrid receive?
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different genetic information for a trait from each parent
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What is a dominant allele?
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covers up or dominates the other trait
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What is a recessive allele?
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the trait seems to disappear
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Probability helps you predict what?
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the chance that something will happen
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A Punnett square can help you predict ____ __ _________ ____ ____ ____.
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what an offspring will look like
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In a Punnett square, what do the upper case letters stand for? Lowercase letters?
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upper case = dominant alleles
lowercase = recessive alleles |
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What is genotype?
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the genetic makeup of an organism
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What is a homozygous?
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an organism with two alleles for one trait that are the same
(written TT or tt) |
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What is a heterozygous
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an organism with two alleles for one trait that are different
(written Tt) |
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What is phenotype?
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the way an organism looks and behaves as a result of its genotype
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How do heredity and genetics explain why people are different?
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People are hybrids. We receive different genetic information form each of our parents. Our parents carry different alleles for the same trait. These alleles can combine in different ways to create different traits in people.
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What is incomplete dominance?
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neither allele for a trait is dominant and the phenotype produced is intermediate between the two homozygous parents
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What are multiple alleles?
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more than two alleles that control a trait
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Traits controlled by multiple alleles produce more than _____ phenotiypes.
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three
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What is polygenic inheritance?
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a group of gene pairs acts together to produce a trait, which creates more variety in phenotypes
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Many human traits are controlled by _________ __________, such as hair and eye color.
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polygenic inheritance
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What are mutations?
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genes that are altered or copied incorrectly
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A mutation can be _______, __________, or ____ __ ______.
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harmful; beneficial; have no effect
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What are chromosome disorders caused by?
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more or fewer chromosomes than normal
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What is down's syndome caused by?
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an extra copy of chromosome 21
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When does a recessive genetic disorder occur?
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When both parents have a recessive allele responsible for the disorder and pass it to their child.
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For recessive genetic disorders, why do the parents not show any symptoms?
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because the parents are heterozygous
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______ ________ is a homozygous recessive disorder.
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cystic fibrosis
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Chromosomes that determine the sex of an organism are __ in females and __ in males.
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XX; XY
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Females produced eggs with an _ chromosome only. Male produce sperm with either an _ or _ chromosome.
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X; X;Y
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What is a sex-linked gene?
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an allele inherited on an X or Y chromosome
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What is a sex-linked disorder caused by a recessive allele on the X chromosome?
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color blindness
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What does a pedigree follow?
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a trait through generations of a family
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How does your environment affect your hereditary traits?
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Although genes determine many of your traits, you may be able to influence their expression by the decisions you make. For example, you may have genes that put you at risk for developing skin cancer, but if you limit your exposure to the sun, you may never develop skin cancer.
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What is genetic engineering?
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changing the arrangement of DNA that makes up a gene
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What is Recombinant DNA?
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Insertion of useful segment of DNA into a bacterium
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What is made by genetically engineered orgainisms?
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insulin
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What is gene therapy?
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a normal allele is placed into a virus, which delivers the normal allele when it infects its target cell
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What can gene therapy be used to control?
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cystic fibrosis or other genetic disorders
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How are genetically engineered plants created?
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by inserting the genes that produce desired traits in one plant into a different plant
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Explain how gene therapy could control cystic fibrosis and other genetic disorders.
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People with cystic fibrosis have received faulty genetic information from their parents. Their genes tell their bodies to create thick mucus rather than thin fluid to lubricate the lungs. Gene therapy can be used to infect their cells with viruses carrying normal alleles with correct genetic information.
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Unlike animal cells, plant cells have what?
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cell wall
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What does the cell wall do?
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provides structure and protection
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Most plant cells contain the green pigment called what?
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chlorophyll
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What is photosynthesis?
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process where plants use chlorophyll to make food
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Where is chlorophyll found?
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in a cell structure called a chloroplast
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What is most of the space inside many plant cells taken up by?
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a large, membrane-bound structure called a central vacuole
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What does the central vacuole do?
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regulates water content
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Where do scientests think plants probably evolved from?
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green algae in the sea
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Why do scientists think plants probably evolved from green algae?
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because plants and green algae have the same types of chlorophyll and carotenoids and fossils of early plants are similar to the ancient green algae
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When plants moved to land, they had to adapt to new conditions like:
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more sunlight and carbon dioxide
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What did plants develop to adapt to new land conditions?
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a waxy cuticle
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What is a cuticle?
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a waxy, protective layer secreted onto the surface of the plant which hold water in and allows plants to live in drier conditions
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What did cell walls develope?
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cellulose
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What is cellulose?
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a chemical compound that provides structure and support, which allows plants to stand upright on land
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What enabled plants to reproduce on land?
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water-resistant spores and seeds
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What do vascular plants use that carry water and nutrients throughout the plant?
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tubelike structures
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Nonvascular plants lack ________ __________ and use other ways to move water and nutrients.
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tubelike structures
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How are plant cells different from animal cells?
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They contain cell walls, chlorophyll, and chloroplasts. They perform photosynthesis.
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What are nonvascular plants?
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very small plants that have rhizoids rather than roots
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In nonvascular plants, how is water absorbed and distributed?
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directly through cell membranes and cell walls
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Where do nonvascular plants grow?
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in damp environments
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How do nonvascular plants reproduce?
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by spores
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What are three nonvascular plants?
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mosses, liverworts, and hornworts
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What are mosses?
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green, leaflike growths arranged around a central stalk
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What are liverworts?
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flattened, leaflike bodies
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What are hornworts?
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have only one chloroplast in each of their cells
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What are pioneer species?
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organisms that are the first to grow in new or disturbed areas which change environmental conditions
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