Chapter 8 DNA Replication, Binary Fission, and Mitosis
Why does DNA replicate?
DNA replicates before a cell divides so that each daughter cell receives a complete set of genetic information.
Cytosine (C) pairs with
Guanine (G)
What separates the 2 strands
Helicase enzyme
binary fission
Replication and division of a prokaryotic cell's DNA into two daughter cells.
What are the events of binary fission?
The cell's DNA replicates, and the two chromosomes attach to the cell membrane. The cell grows between the two attachment points, pulling the two chromosomes apart. The cell wall and cell membrane then pinch inward, dividing the cell into two identical daughter cells.
Adenine (A) pairs with
Thymine (T)
cytokinesis in plant cells
a dividing plant cell must therefore construct a new wall that seperates the two daughter cells.The first sign is the cell plate - a structure that appears at the midline of the dividing plant cell.
Gamete
a sex cell; sperm or egg cell
spindle
a structure of microtubules that aligns and separates chromosomes in mitosis or meiosis
What happens at cell cycle checkpoints?
cell cycle checkpoints ensure that key steps in interphase and mitosis have been successfully completed before the next step begins. If a cell does not successfully pass a checkpoint, the cell cycle may stop, or the cell may enter apoptosis and die.
why are both cell division and apoptosis necessary for the growth and development of an organism?
cell division produces the new cells that make up an organism. Apoptosis carves out structures such as fingers and toes; it also protects an organism by eliminating damaged cells that might otherwise become cancerous.
What do chromosomes consist of?
chromatin
Chromatin
collective term for all of the DNA and its associated proteins in the nucleus of a eukaryotic cell.
Meiosis
division of genetic material that halves the chromosome number and yields genetically variable nuclei.
Mitosis
division of genetic material that yields two genetically identical nuclei.
Telophase
final stage of mitosis in which chromosomes arrive at opposite poles and nuclear envelopes form
Cytokinesis in animal cells
first sign is the cleavage furrow, a slight indentation around the middle of the dividing cell
G2 phase
gap stage in interphase in which the cell makes it final preparations for division
G1 phase
gap stage of interphase in which the cell grows and carries out basic functions
functions of mitotic cell division
grows, repairs damage tissues, some species can regenerate lost body parts, other organisms reproduce asexually by mitotic cell division.
What holds the two strands of DNA together?
hydrogen bonds
Chromosomes
individual molecules of DNA with their associated proteins.
What are the three main events of the cell cycle
interphase, mitosis, cytokinesis
adults produce gametes by
meiosis
Difference between mitosis and cytokinesis
mitosis is the division of duplicated chromosomes into new daughter nuclei. Cytokinesis is the division of cytoplasm and organelles into two new daughter cells.
Explain the roles of mitotic cell division, meiosis, and fertilization in the human life cycle.
mitotic cell division allows for tissue repair/replacement and for an organism's development from a fertailized egg (zygote) to an adult. Meiosis creates genetically variable nuclei that each contain half the genetic material of the rest of the bodys cells. The nuclei may be packaged into gametes; the male gamete fertilizes the female gamete during sexual reproduction, forming a zygote with a full set genetic material.
place the following terms in order from smallest to largest: cell, nucleotide, nucleus, nucleosome, histone, chromosome.
nucleotide, histone, nucleosome, chromosome, nucleus, cell
How does prokaryotes reproduce?
occurs by binary fission, an asexual process that replicates DNA and distributes it into daughter cells.
asexual reproduction
one cell replicates its genetic material and splits into two. Generates identical offspring.
Chromatid
one of two identical DNA molecules that make up a replicated chromosome
egg cells
produced by females
apoptosis
programmed cell death that is a normal part development
Kinetochore
protein that attaches a chromosome to the spindle in cell division
G0 phase
resting phase of the cell cycle in which the cell continues to function but does not divide.
cell cycle
sequence of events that occur in an activity dividing cell
centromere
small section of a chromosome where sister chromatids attach to each other.
Metaphase
stage of mitosis in which chromosomes are aligned down the center of a cell
Anaphase
stage of mitosis in which the spindle pulls sister chromatids toward opposite poles of the cell
Prometaphase
stage of mitosis just before metaphase, when the nuclear membrane breaks up and spindle fibers attach to kinetochores
Prophase
stage of mitosis when chromosomes condense and the mitotic spindle begins to form
Interphase
stage preceding mitosis or meiosis, when the cell carries out its functions, replicates its DNA, ans grows
nucleosomes
the basic unit of chromatin; consists of DNA wrapped around eight histone proteins.
What happens during interphase?
the cell grows and produces protein needed to carry out its functions, In addition DNA replicates as the cell prepares to divide
Cytokinesis
the cell splits into two daughter cells.
sexual reproduction
the production of offspring whose genetic makeup comes from two parents. Each parent contributes a sex cell, and the fusion of these cells signals the start of the next generation.
S phase
the synthesis phase of interphase, when DNA replicates
Fertilization
the union of two gametes. Union of the sperm and the egg cell, producing a zygote.
How many chromosomes do humans have?
46
Genome
All the genetic material in an organism. (set of cookbooks)
What is the difference between a benign and a malignant tumor?
Benign tumors are surrounded by a capsule; they do not spread to other areas of the body or invade nearly tissues. A malignant tumor invades nearby tissues and may metastasize, spreading to other areas of the body.