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151 Cards in this Set
- Front
- Back
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William Harvey (1600's): Theory of Epigenesis |
An organism develops from a fertilized egg through developmental events, transforming the egg into an adult. |
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Schleiden and Schwann (1830): The Cell Theory
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All organisms are composed of cells derived from preexisting ones.
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spontaneous generation |
Louis Pasteur disproved this idea. Creation of living organisms from nonliving components
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natural selection |
Charles Darwin’s travels on the HMS Beagle provided him geological, geographical, and biological observations that helped formulate this theory. He believed existing species arose from other ancestral species by descent with modification. Existing species arose from other ancestral species by descent with modification. Natural selection was based on the observation that populations tend to contain more offspring than the environment can support and those with heritable traits can survive and reproduce more than those without these traits. If this population becomes isolated, a new species may result.
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Mendel |
Mendel worked with peas and used quantitative data to show that traits are passed from parents to offspring in predictable ways. he concluded that each trait is controlled by a pair of genes that separate during gamete formation.Mendel published his findings (1866) offering a general model of how traits are passed, but his work was largely unknown.
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most eukaryotes are |
diploid, Advances in microscopy have identified chromosomes (Figure 1-2) and establish that most eukaryotes are diploid |
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Diploid number |
2n, is the number of chromosomes in each species of most eukaryotes. |
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Humans have a diploid number of |
46 |
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Eukaryotic cells undergo two types of cell division:
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Mitosis and meiosis. Mitosis: chromosomes are copied and distributed so that each daughter cell receives a set of chromosomes identical to those in the parental cell. Two resulting daughter cells receive a diploid set of chromosomes Meiosis: associated with gamete formation. Cells produced by meiosis receive only one chromosome from each chromosome pair, the number of chromosomes is the haploid number. This reduction of chromosomes is essential if the offspring is maintaining the number of chromosomes from their parents. Resulting cells (gametes) receive only half the number of chromosomes (haploid, n).
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chromosomal theory of inheritance |
(Sutton and Boveri) states that inherited traits are controlled by genes residing on chromosomes. They noted that the behavior of chromosomes during meiosis is identical to the behavior of genes during gamete formation described by Mendel. Proposed that genes are carried on chromosomes. So they formed this theory which states that inherited traits are controlled by genes residing on chromosomes transmitted through gametes maintaining genetic continuity throughout generations.
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Alternate forms of a gene are called |
alleles. Different alleles may produce differences in the phenotype of an organism. |
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mutation |
any heritable change in the DNA sequence and is the source of all genetic variation. Because of mutations there are variations in genes/alleles (DNA sequences). |
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what is the source of genetic variation |
mutations |
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genotype |
The set of alleles for a given trait |
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phenotype |
The expression of the genotype produces an observable trait |
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Who is the carrier of genetic information and how? |
DNA (nucleic acid), not protein, is the carrier of genetic information. Research of Avery, MacLeod, and McCarty: 1944 -First scientists believed protein carried genetic info because of their universal distribution in the nucleus and the cytoplasm, however after much research especially on bacteria and viruses, evidence was found which proved that DNA not protein carried genetic material.
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The structure of DNA was described by |
Watson and Crick (1953). They described DNA as a long ladder-like macromolecule that twists to form a double helix.
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DNA structure |
DNA is an antiparallel, double-stranded helix. is made up of nucleotides, Sugar bonded to a phosphate and four bases (Adenine, cytosine, guanine, and thymine). These nucleotides form A≡T and G=C complementary base pairing across the helix
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RNA (nucleic acid) is similar to DNA, except that:
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it is usually single-stranded.
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central dogma of genetics |
Transcription first then translation. is gene expression. look up on internet to make sure. |
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Transcription |
Transcription is the process by which the information on a DNA strand is transcribed into a messenger RNA (mRNA). In eukaryotic cells this process begins in the nucleus. The nucleotide sequence in one strand of DNA is used to construct a complementary RNA sequence creating an RNA molecule. Then the RNA molecule moves to the cytoplasm where the RNA (mRNA) binds to a ribosome.
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Translation |
the synthesis of proteins where the information in the mRNA is translated into a protein |
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genetic code |
info encoded in mRNA. consists of triplet nucleotides present in mRNA.
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codon |
Each triplet (codon) encodes for insertion of a specific amino acid into a growing protein chain.
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how many amino acids are found in proteins |
20 |
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end products of gene expression |
proteins |
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Once a protein is made, its action or location in a cell plays a role in producing a |
phenotype |
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What are the largest category of proteins?
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enzymes |
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Mutations altering a gene may |
modify, alter, or even eliminate the protein’s usual function and cause an altered phenotype.
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Sickle-cell anemia results from |
a mutation in the gene encoding β-globin, resulting in an amino acid substitution. Sickle-shaped red blood cells are deformed and fragile and break easily, leading to a whole series of physical and physiological problems |
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restriction enzymes |
In the 1970s researchers discovered restriction enzymes in bacteria that cut viral DNA at specific sites. Can be used to cut any organism's DNA at specific nucleotide sequences producing a reproductible set of fragments. These fragments are then inserted from restriction enzymes into vectors which are carrier DNA molecules.
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importance of recombinant DNA and restriction enzymes |
With the use of vectors, restriction enzymes have allowed the advent of recombinant DNA and cloning.
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Biotechnology |
the use of recombinant DNA technology and other molecular techniques to make products. |
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importance of biotechnology |
allows for genetically modifying crop plants to improve agriculture by using genes for traits such as resistance to herbicides, insects, and nutritional enhancement, which have been introduced into crop plants. use of transgenic organisms which are used to synthesize therapeutic proteins. is used for cloning livestock to produce dozens of offspring with desirable traits. used for medicine to test for prenatal diagnosis of heritable disorders, if parents are carriers, if their children will be affected and the risk of them as parents developing a genetic disorder.
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transgenic organisms |
type of organisms created by the transfer of heritable traits across species using recombinant DNA technology |
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Genomics |
analyzes genome sequences to study the structure, function, and evolution of genes and genomes.
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Proteomics |
identifies a set of proteins present in cells under a given set of conditions and studies their function and interactions.
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Bioinformatics |
develops hardware and software for processing nucleotide and protein data.Used to store, retrieve, and analyze the data generated by genomics and proteomics.
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model organisms |
organisms used for the study of basic biological processes. The genetics of model organisms can be applied to humans for understanding and treating human diseases.
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what made an organism a good model organism? |
Easy to grow Same genetic mechanisms in most organisms characteristics suitable for genetic research |
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All life has a common origin, and genes with similar functions in different organisms are similar in |
structure and DNA sequence.
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gene transfer |
By transferring genes between species, scientists have developed models of human diseases in organisms ranging from bacteria to fungi, plants, and animals (Table 1.2).
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section 1.8 random facts |
The field of genetics started with Mendel’s presentation of his research on peas in 1865.
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Escherichia coli |
the best-understood living organism Easy to grow, manipulate, and mutagenize
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Saccharomyces cerevisiae
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Simple eukaryote
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Arabidopsis thaliana (a mustard plant)
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Model for crop plants
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Drosophila melanogaster
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Easy to grow and manipulate (9 days from egg to adult at 25oC)
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Caenorhavditis elegans
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Easy to manipulate
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Mus musculus
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Easy to breed mammal
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Which of the following correctly indicates the relationship between genes and chromosomes? A gene is composed of DNA complexed with proteins, and many chromosomes are found along the length of a single gene.Or A chromosome is composed of DNA complexed with proteins, and many genes are found along the length of a single chromosome. |
A chromosome is composed of DNA complexed with proteins, and many genes are found along the length of a single chromosome. |
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How is genetic information encoded in a DNA molecule? |
Genetic information is encoded in DNA by the sequence of bases. |
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Which of the following correctly depicts the central dogma of molecular genetics?
RNA → DNA→ protein RNA → protein→ DNA DNA → RNA → protein |
DNA → RNA → protein |
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How many different proteins, each composed of 8 amino acids, can be constructed using the 20 different amino acids found in proteins? |
2.56×1010 |
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The theory of epigenesis states that |
adult structures in the organism develop de novo from substances present in the egg |
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The functional unit of heredity is a |
gene |
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What are the basic subunits of DNA and RNA? |
nucleotides |
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Arabidopsis is a model organism for the study of |
plants |
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Is it possible for more than two alleles of a gene to exist? |
Yes. There can be many such variants in a population, but for a diploid organism, only two such alleles can exist in any given individual. |
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The immediate product of transcription is |
RNA |
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why is it bad if a model organism has a long life span? |
Correct It is preferable for model organisms to have short life spans, so that their development and aging can be studied within a short period of time. |
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All living organisms contain genetic material which, except in some viruses, is made of |
the nucleic acid DNA.
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DNA is organized into units called |
genes whose products direct metabolic activities of cells.
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DNA is organized into |
chromosomes |
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In eukaryotes, transmission of genetic material from one generation of cells to the next involves |
mitosis and meiosis |
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Mitosis |
leads to production of two cells, each with the same number of chromosomes as the parent cell (2n). It is the portion of the cell cycle which hereditary components are equally divided into daughter cells.
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Meiosis |
leads to production of gametes, which contain half the number of chromosomes (n). Reduces the genetic content and the number of chromosomes to half which is essential if sexual reproduction is to occur without doubling the amount of genetic material at each generation. Part of a special type of leads to the production of gametes (sex cells).
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gametes/spores |
sex cells created during meiosis. helps the transmission of genetic info from an organism to offspring. |
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are visible as condensed structures during mitosis and meiosis.
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chromosomes |
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chromatin |
Uncoiled chromosomes that form a diffuse network with the nucleus.The nucleus contains DNA which is complexed with an array of acidic and basic proteins into thin fibers called chromatin. condenses into chromosomes during mitosis and meiosis. contains the nucleolus
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two main types of cells |
Prokaryotic (bacteria, archaea)
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All cells share some common features:
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Plasma membrane
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plasma membrane |
all cells are surrounded by this. is an outer covering that defines the cell boundary and delimits the cell from its immediate external environment. It controls the movement of materials into and out of the cell. covered by glococalyx |
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glycocalyx/cell coat |
a covering over the plasma membrane made up of glycoproteins and polysaccharides which differs from the structures in plants or bacteria. Found in most animal cells. It defines the biochemical identity of each cell.
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cell wall |
an outer covering made up of a polysaccharide called cellulose for plants. Bacterial cells have peptidoglycan on their cell wall.
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nucleolus |
an amorphous component in the nucleus where ribosomal RNA (rRNA) is synthesized and where the initial stages of ribosomal assembly occur. |
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nucleus is surrounded by a |
nuclear membrane |
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Prokaryotic cells lack a |
nuclear membrane and membrane-bound organelles.They don't have a distinct nucleolus but they do contain genes that specify rRNA molecules.
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nucleoid |
in prokaryotic cells that make up a large chunk f it and is compacted with circular DNA that does not undergo coiling characteristics of the stages of mitosis where in eukaryotes, chromosomes become visible and NOR is the DNA associated with proteins like eukaryotic DNA |
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cytoplasm |
the remainder of the eukaryotic cell enclosed by the plasma membrane excluding the nucleus and other cellular organelles. Cytoskeleton provides structure to cytoplasm.
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cytoskeleton |
provides structure to cytoplasm. |
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Endoplasmic reticulum |
is an organelle that compartmentalizes the cytoplasm. increasing the surface area available fro biochemical synthesis. Smooth ER is the site of lipid synthesis. Rough ER is studded with ribosomes that are sites of protein synthesis.
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cytoplasmic structures important in the eukaryotic cell's activities |
mitochondria, chloroplasts, and centrioles. |
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the site of cell respiration and
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Mitochondria, found in both plant and animal cells |
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site of photosynthesis |
Chloroplasts, in plants, algae, and some protozoans |
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Both mitochondria and chloroplasts contain |
DNA similar to prokaryotic DNA.
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Endosymbiotic theory: |
Mitochondria and chloroplasts were once primitive free living organisms that established a symbiotic relationship with a primitive eukaryotic cell. It describes the evolutionary origin of these organelles.
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centrioles |
a pair of complex structures contained in animal and plant cells. in the cytoplasm are located in a specialized region called the centrosome in animal cells
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centrosome |
organize spindle fibers for movement of chromosomes during meiosis and mitosis.
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somatic cells |
contain the same number of chromosomes for members of the same species.
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_____exist in homologous pairs in diploid organisms |
chromosomes |
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chromosomes are most easily visualized during |
mitosis. when they are examined, distinctive lengths and shapes are apparent. |
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centromere |
is a constriction (region) in each chromosome which establishes the general appearance of each chromosome. Depending on the position of the centromere, different arm ratios are produced. It divides the chromosome into two arms |
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p arm |
shorter arm of chromosome, above the centromere |
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q arm |
longer arm of chromosome, below the centromere |
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Each chromosome has |
two sister chromatids |
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Homologous chromosomes |
are similar copies of each other but carry different versions of the same gene (allele). One chromosome of the homologous pair is of paternal origin (via the sperm) and the other is of maternal origin (via the egg).
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karyotype |
illustrates the physical appearance of different pairs of homologous chromosomes. Each chromosome is a double structure consisting of two sister chromatids connected at the centromere.
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haploid number |
The haploid number is half of the diploid number and constitutes the genome of the species. The genetic info in a haploid set of chromosomes constitutes the genome of the species. Includes copies of all genes and nondecoding DNA. |
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Sex-determining chromosomes |
are not homologous in size, centromere placement, arm ratio, or genetic content. Females are XX.
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locus |
Homologous pairs of chromosomes contain identical gene sites along their lengths. So these chromosomes are identical in their genetic potential. |
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for many single-celled organisms, such as protozoans and some fungi and algae, mitosis serves as the basis for
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asexual reproduction |
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In multicellular organisms, mitosis is responsible for |
wound healing, cell replacement, and growth.
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zygotes |
Are single-celled fertilized eggs who later become multicellular diploid organisms. The mitotic activity of zygotes and daughter cells are necessary for development and growth of the organism. |
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karyokinesis |
In Mitosis. Genetic material is partitioned into daughter cells in this or during cell division. In this process chromosomes must first be exactly replicated and partitioned resulting in two daughter nuclei each with a chromosome composition identical to the parent cell. the genetic material is evenly divided into two nuclei. Is followed by cytokinesis. |
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cytokinesis |
This mechanism is needed fro reconstituting the cytoplasm in daughter cells. |
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Cell cycle |
the events that occur from the completion of one division until the beginning of the next division. The cell cycle is composed of interphase (G1, S, G2) and mitosis |
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interphase |
interval between divisions. In this phase, replication of the DNA of each chromosome occurs which is critical to mitosis. the nucleus is filled with chromatin fibers that are formed as the chromosomes are uncoiled and dispersed after the previous mitosis. Once G1, S, and G2 are completed, mitosis is initiated which has continual activity. |
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S phase |
Part of interphase where DNA is synthesized before the cell enters mitosis. |
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Two periods in interphase when no DNA synthesis occurs |
G1 and G2 |
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G1 and G2 occur in |
the cytoplasm |
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By the end of G2 |
the cell has doubled in size (DNA duplicated, mitosis initiated).
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Following mitosis |
continuously dividing cells then repeat this cycle (G1, S, G2, M). |
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G0 |
is a point in the G1 phase where cells withdraw from the cell cycle and enter a nondividing but metabolically active state.Cells taht enter G0 remain viable and metabolically active but are nonproliferative. Cancer cells avoid entering or pass through it quickly. Other cells enter G0 and never reenter the cell cycle. Others remain in G0 but can be stimulated to return to G1 and reenter the cycle.
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G1 |
At a point late in G1, all cells follow one of two paths; either they withdraw from the cycle, become quiescent and enter G0 stage or they become committed to initiating DNA synthesis and completing the cycle. |
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order of stages in mitosis |
prophase, prometaphase, metaphase, anaphase, and telophase. |
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In Mitosis, Prophase |
over half of mitosis is spent here. It is here that the centrioles (in animal cells only) divide and move apart, the nuclear envelope breaks down, the nucleolus disintegrates, and chromosomes condense and become visible. Sister chromatids are visibly connected at the centromere.
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In Mitosis, Prometaphase |
the chromosomes move to the equatorial plane of the cell.
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sister chromatids |
two parts of each chromosome, where the DNA in each of them is genetically identical, having formed from a single replicative event. |
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In Mitosis, metaphase |
the centromeres/chromosomes are aligned at the equatorial plane. chromosome configuration following migration
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In Mitosis, anaphase |
Centromeres split and sister chromatids separate from each other; they are no longer chromatids but chromosomes. For the initation of anaphase to occur, each centromeric region must be split into two and once it occurs each chromatid is a daughter chromosome.
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In Mitosis, telophase |
Telophase is the final stage of mitosis with two complete sets of chromosome, one set at each pole.
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the cell cycle is |
genetically regulated Disruption of regulation can lead to uncontrolled cell division characterizing malignancy.
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Kinases |
are enzymes that serve as a “master control” and bind with cyclins (proteins), activating kinases at appropriate times during the cell cycle to phosphorylate proteins regulating the cell cycle
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cyclins |
are proteins that bind to kinases activating them at times in the cell cycle. |
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cell cycle has 3 major checkpoints |
where processes in normal mitosis are monitored or checked by master control molecules before the next stage of the cycle starts. If the checkpoints fail to recognize and stop the errors, then cell division proceeds and a tumor results.
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In diploid organisms mitosis produces two daughter cells with full diploid complements while___ produces gametes or spores that have one haploid set of chromosomes. |
meiosis |
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Meiosis |
During sexual reproduction, haploid gametes combine at fertilization to be a diploid complement found in parent cells. Meiosis makes sure haploid gametes/spores have one member of each homologous pair of chromosomes and after this is done, meiosis maintains genetic continuity. It also ensures genetic variation during sexual reproduction in two forms; fertilization and crossing over. During fertilization; meiosis produces a large number of chromosome combinations by creating gametes with combos of maternally and paternally derived chromosomes among the haploid complement. has two divisions; meiosis I and meiosis II. Meiosis is a process similar to mitotic prophase, except that homologous chromosomes pair up (synapsis)
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crossing over |
happens in meiosis, it results in genetic exchange between members of each homologous pair of chromosomes that finds its way into a haploid gamete or spore. creates intact chromosomes resembling parents' homologs, enhancing genetic variation. |
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Meiosis Prophase 1 |
It begins with a diploid cell (DNA duplicated during interphase, chromosomes made up of sister chromatids). the cell duplicates its genetic material in the interphase stage preceding chromosome division. To reach haploidy two divisions are required where the first is prophase 1. Is different than mitosis because in meiosis once the chromatin characterizing interphase has condensed into visible structures, the homologous chromosomes are not autonomous but are paired up=synapsis. each synapsed pair of homologs is initially called a bivalent.Not fully condensed chromatin thus the fact that DNA has duplicated is not obvious. As prophase progresses within each tetrad, each pair of sister chromatids is pulled apart but at the chiasma where chromosomes are intertwined one ore more areas remain in contact. on pair of sister chromatids is maternally derived while the other pair is paternally derived.
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bivalent |
number of bivalents is equal to the haploid number. |
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tetrad |
as homologs condense and shorten during prophase 1 of meiosis 1, each bivalent gives rise to this which is two pairs of sister chromatids each joined at a common centromere. Gives visible evidence that both homologs have duplicated. |
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synapsis in prophase 1 of meiosis |
Synapsis gives rise to a tetrad (two pairs of sister chromatids) with overlapping of nonsister chromatids (chiasma). Exchange of genetic material (paternal/maternal chromosomes) through recombination homologous chromosomes pair up
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final period of prophase 1 of meiosis |
Nuclear envelope and nucleolus break down, and the two centromeres of the tetrad attach to the spindle fibers. After Prophase I, steps similar to mitosis occur.
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Metaphase 1 of meiosis 1 |
step after prophase 1. is the first division. chromosomes have maximally shortened and thickened, chiasma are visible, holding nonsister chromatids together. Each tetrad interacts with spindle fibers giving movement to the metaphase plate.
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Anaphase 1 of meiosis 1 |
Alignment of chromosomes at the metaphase plate is random; half of each tetrad (Dyad) is randomly pulled (disjunction) to opposite poles (Anaphase I).
completion of anaphase 1: dyads equal to the haploid number is present at each pole where because of crossing over in prophase, chromatids have both paternal and maternal origin.
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disjunction |
separation of chromosomes |
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Telophase 1 of meiosis 1 |
is marked with the reappearance of the nuclear membrane forming around the dyads and the nucleus enters a short interphase where
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Prophase II of meiosis |
Chromosomes/each dyad are composed of one pair of sister chromatids attached by a common centromere.
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Metaphase II of meiosis |
Centromere is positioned at the metaphase plate. When they divide anaphase II is initiated. |
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Meiosis II |
is essential if each gamete or spore needs to receive only one chromatid from each original tetrad. |
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Anaphase II of meiosis |
Centromeres divide; sister chromatids of each dyad are pulled to opposite poles.
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Telophase II |
Similar to mitotic telophase. Because the number of dyads=haploid number, this stage reveals one member of each pair of homologous chromosomes at each pole. Cytokinesis results in four haploid gametes with equal cytoplasm, containing a combination of maternal and paternal genes.
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Completion of Meiosis II |
Haploid state achieved if crossing over has occured, each monad is a combo of maternal and paternal genetic info, where offspring produced by any gamete has a mixture of genetic info orig. present in his/her grandparents. increases genetic variation in each generation. |
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Spermatogenesis takes place in the |
testes. |
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Oogenesis takes place in the |
ovary |
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spermatogenesis |
production of male gamete. Begins with growth of spermatogonium (undifferentiated germ cell) and then it becomes/enlarges into a primary spermatocyte which undergoes the first meiotic division. Then haploid secondary spermatocytes are produced which then undergoes meiosis II where each produces two haploid spermatids (a total of four haploid spermatids that undergo a series of developmental changes, spermiogenesis, and become highly specialized, motile spermatozoa or sperm).
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All sperm cells produced during spermatogenesis contain the ____ of chromosomes and ____ amounts of cytoplasm |
haploid, equal |
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Oogenesis |
Formation of ova (eggs). Daughter cells from two meiotic divisions recieve equal genetic material but not equal amounts of cytoplasm. An undifferentiated germ cell called an oogonium enlarges to become a primary oocyte. The secondary oocyte undergoes meiosis II and produces two haploid cells: an ootid with the bulk of cytoplasm and a second polar body.
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_____ is critical to the successful sexual reproduction of all diploid organisms. and why?
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Meiosis, and it produces haploid gametes. Crossing over in Meiosis I Prophase I reshuffles alleles between homologous maternal and paternal chromosomes which segregate and assort independently into gametes.
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Meiosis plays a significant role in the life cycle of fungi and plants.
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In many fungi, the predominant stage of the life cycle consists of haploid vegetative cells that arise through meiosis and proliferate through mitosis. Meiosis and fertilization are the bridge between these two stages.
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Electron microscopy |
shows why chromosomes are invisible during interphase but visible during mitosis and meiosis: Electron microscopy has revealed that once mitosis/meiosis begins, chromatin fibers coil and fold, condensing into typical metaphase chromosomes (Figure 2-13).
Electron microscopic observations of mitotic chromosomes in varying states of coiling led to the postulation of the folded-fiber model (Figure 2-13c).
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