BIO 1114 - Ch 8 - DNA Replication, Binary Fission, and Mitosis
Steps of DNA replication
1) the helicase enzyme unwinds and separates the two DNA strands 2) the DNA polymerase enzyme assembles new DNA strands using nucleotides that are complementary to each exposed strand 3) the process ends with two identical double stranded DNA molecules
Which of the following undergo mitosis? Germ-line cells Fertilized cells Skin cells Muscle cells
2-4
malignant tumor
A cancerous tumor that is invasive enough to impair the functions of one or more organs.
Where does DNA come from?
A cell can copy its own DNA
binary fission
A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size
sexual reproduction
A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents
Gene
A segment of DNA on a chromosome that codes for a specific trait
Meiosis
A specialized type of cell division that gives rise to nuclei that are genetically different from one another
What are the four bases of DNA?
Adenine, Thymine, Cytosine, Guanine
DNA polymerase
An enzyme that catalyzes the formation of the DNA molecule.
If the genetic material in a cell is damaged behind repair, a signaling protein may trigger _____
Apoptosis
Centromere
Area where the chromatids of a chromosome are attached
Genetic mutations cause a key role in causing ____
Cancer
G2 phase of interphase
Cell continues to grow but also prepares to divide, producing the proteins that will help coordinate mitosis
Interphase
Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases
Cytokinesis in animal cells
Cell membrane is drawn inward until the cytoplasm is pinched into two nearly equal parts The two nuclei are distributed into two forming daughter cells, which then physically separate Cleavage furrow forms
Anaphase (Mitosis)
Centrosomes split as sister chromatids separate and move to opposite poles of cell. At the same time, some microtubules in the spindle lengthen in a way that moves the poles further apart, stretching the cell
What's a collective term for all of the cell's DNA and its associated proteins?
Chromatin
Early Prophase (Mitosis)
Chromatin in nucleus condenses to form visible chromosomes, mitotic spindle forms from fibers in cytoskeleton or centrioles (animal). Centrosomes move to opposite poles
Metaphase (mitosis)
Chromosomes line up in the middle of the cell
homologous chromosomes
Chromosomes that have the same sequence of genes and the same structure that come from each parent
Components of chromatin
DNA proteins for scaffolding Proteins for replication Proteins for transcription
Before a cell's nucleus and cytoplasm can split in two...
DNA replication must happen
A cell must package its DNA into a portable form that can easily move into the two ____ cells
Daughter
Each cancerous cell passes krs loss of cell cycle control to its _______ cells
Daughter
What does radiation therapy do?
Destroys cancer cells with minimal damage to normal cells
What does DNA polymerase do?
Discards mismatched nucleotides and inserts correct ones
Mitosis
Divides a eukaryotic cell's genetic information into two identical nuclei
What do cell cycle checkpoints do?
Ensure that a cell doesn't enter one stage or the cell cycle until the previous stage is complete
What copies DNA?
Enzymes called DNA polymerase
S phase of interphase
Enzymes replicate the cell's genetic material and repair damaged DNA
True or false: DNA replication occurs simultaneously at one point along a chromosome
False. Across many points
True or false: chemical signals that regulate the cell cycle don't have to be orecise
False. It's essential that it's precise
True or false: the daughter dells of mitosis have half as many chromosomes as the parent cell
False. They have the same amount
Ligase enzyme
Forms covalent bonds between adjacent DNA segments
Cytosine pairs with
Guanine (G)
Gern-line cells divide to produce
Haploid cells called gametes
The two members of a chromosome pair in diploid cells are called
Homologous chromosomes
What holds the strands of the DNA double helix together?
Hydrogen bonds between purines and pyrimidines.
sister chromatids
Identical copies of a chromosome; full sets of these are created during the S subphase of interphase
cell plate
In a plant cell, midline of dividing cells. Becomes the cell wall eventually.
A cell spends most of its cycle during _____
Interphase
What part of the cell cycle begins immediately after interphase?
Mitosis
Late Prophase (Mitosis)
Nuclear membrane & nucleolus are broken down; chromosomes continue condensing & are clearly visible; spindle fibers called kinetochores attach to the centromere of each chromosome
Each strand of the double helix of DNA is composed of
Nucleotides
Examples of benign tumors
Papilloma (wart), Adenoma, Lipoma, Osteoma, Myoma, Angioma, Nevus, Meningioma, Chondroma
Does DNA replication precede or proceed cell division?
Precede
asexual reproduction
Process by which a single parent reproduces by itself
Fertilization
Process in sexual reproduction in which male and female reproductive cells join to form a new cell
DNA is transcribed into
RNA
Centromere
Region of a chromosome where the two sister chromatids attach
Chromatin are enzymes that help DNA do what?
Replicate it and transcribe it to RNA
Some cell cycle checkpoints
Screen for damaged DNA
origins of replication
Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.
Most familiar forms of cancer
Solid tumors of the breast, lung, skin and other major organs
Centrosome
Structures that organize the mitotic spindle
Chromatin
Substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones
Traditional cancer treatment includes
Surgical removal, chemotherapy, radiation
DNA replication in preparation for cell division also requires
That the cell's DNA be unwound
daughter cells
The cells that are produced as a result of mitosis. These cells are identical to each other, and also to the original parent cell.
Adenine pairs with
Thymine (T)
Since cell division and cell death are in balance...
Tissue neither overgrows or shrinks
DNA's main function
To specify the recipes for all the proteins in a cell
True or false: a malignant tumor lacks a surrounding capsuke
True
True or false: cancer arises when cells divide out of control
True
True or false: many protists and multicellular eukaryotes also reproduce asexually
True
Benign tumors
Usually slow growing and harmless, unless they become large enough to disrupt nearby tissues or organs A tough capsule surrounding the tumor helps it from invading nearby tissues or spreading to other parts of the body
Zygote
a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum
checkpoints in cell cycle
after G1, G2, metaphase
Genome
all of an organism's genetic material
Cancer
any malignant growth or tumor caused by abnormal and uncontrolled cell division.
G1 phase of interphase
cell grows: increase in size and synthesize new proteins and organelles
paired sister chromatids are joined to each other at the
centromere
Mutation
change in a DNA sequence that affects genetic information
cytokinesis in plant cells
divide from inside out using a cell plate in middle of cell
germ line cells
during zygote development, cells that are set aside from the somatic cells and that will eventually undergo meiosis to produce gametes
spindle
fanlike microtubule structure that helps coordinate the movement of chromosomes during mitosis
Meiosis produces
four genetically different haploid cells
Asexual reproduction generates
genetically identical offspring
three stages of eukaryotic cell cycle
interphase, mitosis, cytokinesis
What does chemotherapy do
kills rapidly dividing cells
tumor
mass of rapidly dividing cells that can damage surrounding tissue
What process accounts for the formation of a multicellular adult from a zygote and for asexual reproduction in protists and other eukaryotes?
mitosis
Cancer begins when
mutations of a single cell disrupt the normal cell cycle, causing cells to divide in an uncontrolled way
DNA is a double stranded
nucleic acid
Chromatids
one of two identical "sister" parts of a duplicated chromosome
Apoptosis
programmed cell death
Histones
protein molecules around which DNA is tightly coiled in chromatin
Nucleosome
repeating subunit of chromatin fibers, consisting of DNA coiled around 8 histones
In a human body, mitotic cell division occurs about 300 million times per minute and acts to
replace cells
cell cycle
series of events that cells go through as they grow and divide
After DNA replication chromosomes consist of two
sister chromatids
Gametes
sperm and egg cells
The _____ consists of microtubule fibers that move the chromosomes during mitosis
spindle
cleavage furrow
the first sign of cytokinesis during cell division in an animal cell; a shallow groove in the cell surface near the old metaphase plate
Telophase (mitosis)
the nuclei for the newly split cells form, the nucleoli reappear, and the chromosomes uncoils. Spindle disappears As this phase ends, the division of the genetic material is complete and the cell contains two nuclei- but not for long
metastasize
the process by which cancer spreads from one place to another
Sexual life cycle
the production of haploid gametes by meiosis, followed by the union of two gametes in sexual reproduction
Chromosomes
threadlike structures made of DNA molecules that contain the genes
Diploid cells contain
two complete sets of chromosomes