Term
| What depends on cell division? |
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Definition
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Term
| In cell division, what must parent cells provide ? |
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Definition
| Their daughter cells DNA and enough cytoplasmic machinery to start up their own operation. |
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Term
| What are the types of cell division in eukaryotic cells? |
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Definition
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Term
| What is the type of cell division in prokaryotic cells? |
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Definition
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Term
| Cell division in prokaryotes takes place in two stages, what are they? |
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Definition
| 1. The DNA is replicated
2. The cell elongates, then splits into two daughter cells
The process together is called binary fission |
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Term
| Why is cell division in eukaryotes more complex than in prokaryotes? |
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Definition
| 1. Eukaryotic contain far more DNA
2. Eukaryotic DNA is packaged differently |
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Term
| How is eukaryotic DNA packaged? |
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Definition
| It is in linear chromosomes compacted with proteins. |
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Term
| Eukaryotic cells divide in one of two ways and with different cells...what are they? |
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Definition
| Mitosis : Occurs in somatic (non-reproductive) cells
Meiosis: Occurs in germ (reproductive) cells |
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Term
| What does Meosis produce? |
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Definition
| Results in the production of gametes |
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Term
| What increase...and what duplicates in the cell cycle? |
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Definition
| During cycle, cell increases in mass and duplicates its chromosomes. |
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Term
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Definition
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Term
| What are the stages of a Eukaryotic cell? |
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Definition
| G1 phase:
Primary growth phase
S phase:
DNA replication
G2 phase:
Microtubule synthesis
M phase:
Chromosomes pull apart
C phase:
Cytoplasm divides |
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Term
| What are the 4 characteristics of interphase? |
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Definition
| 1. Usually longest part of the cycle
2. Cell increases in mass
3. Number of cytoplasmic components doubles
4.DNA is duplicated |
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Term
| What are the stages of interphase? |
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Definition
G1:
Interval or gap after cell division
S:
Time of DNA synthesis (replication)
G2:
Interval or gap after DNA replication |
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Term
| What are the stages of mitosis? |
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Definition
| Prophase
Metaphase
Anaphase
Telophase |
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Term
| What is mitosis usually followed by? |
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Definition
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Term
| Hwo many chormosomes are in each species? |
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Definition
| The number of chromosomes varies enormously from species to species. |
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Term
| What is the name of the chromosmal pair? |
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Definition
| Chromosomes exist in somatic cells as pairs also called homologous chromosomes or homologues. |
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Term
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Definition
| Chromosomes are molecules of DNA complexed with proteins (histones).
Between divisions, each threadlike chromosome is duplicated to form sister chromatids.
Chromatids are joined by a centromere—the region where the chromosome will attach to microtubules during nuclear division. |
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Term
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Definition
| Have two copies of each chromosomes |
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Term
| What are the chromosomes held topgether by? |
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Definition
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Term
| How many chromosome do humans have? |
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Definition
| Humans have 46 chromosomes
The 23 pairs of homologous chromosomes can be organized by size
This display is termed a karyotype |
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Term
| What are chromosomes made of? |
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Definition
| Chromosomes are composed of chromatin
Complex of DNA (~ 40%) and proteins (~ 60%)
A typical human chromosome contains about 140 million nucleotides in its DNA
In the cell, however, the DNA is coiled |
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Term
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Definition
| The DNA helix is wrapped around positively-charged proteins, that the DNA helix is wrapped around. |
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Term
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Definition
| 200 nucleotides of DNA coil around a core of eight histones. |
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Term
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Definition
| What the nucleosomes coil |
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Term
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Definition
| What solenoids are organized into. |
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Term
| What is the eukaryaotic stages? |
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Definition
Interphase
Mitosis
Division of the nucleus, also termed karyokinesis
Subdivided into
Prophase, metaphase, anaphase, telophase.
Cytokinesis - division of the cytoplasm |
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Term
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Definition
| Consists of two distinct sets of microtubules - Each set extends from one of the cell poles.
Two sets overlap at spindle equator
Moves chromosomes during mitosis |
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Term
| What happens to chromosomes during interphase? |
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Definition
| Chromosomes replicate and begin to condense. |
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Term
| What happens during prophase? |
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Definition
| Nuclear envelope breaks down
Chromosomes condense further
Spindle apparatus is formed |
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Term
| What happens during metaphase? |
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Definition
| Chromosomes align along the equatorial plane
Spindle fibers attach at the kinetochores
On opposite sides of the centromeres |
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Term
| What happens during anaphase? |
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Definition
| Sister chromatids separate
They are drawn to opposite poles by shortening of the microtubules attached to them |
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Term
| What happens during telophase? |
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Definition
| Nuclear envelope reappears
Chromosomes decondense
Spindle apparatus is disassembled |
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Term
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Definition
| Two diploid daughter cells form |
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Term
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Definition
| Pinches the cell in two. In an animal cell. |
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Term
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Definition
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Term
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Definition
| (Eggs and sperm) contain half the complement of chromosomes found in other cells |
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Term
| What is the fusion of gametes called? And what does it create? |
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Definition
| Fertilization or syngamy
It creates the zygote, which contains two copies of each chromosome |
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Term
| What does sexual reproduction contain? |
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Definition
| Involves the alternation of meiosis and fertilization., however Asexual reproduction does not. |
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Term
| What does the life cycles of all sexually-reproducing organisms include? |
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Definition
| It follows the same basic pattern.
Haploid cells or organisms alternate with diploid cells or organisms |
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Term
| What stages does meoisis seperate? |
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Definition
Meiosis I
Separates the two versions of each chromosome
Meiosis II
Separates the two sister chromatids of each chromosome |
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Term
| What deoes meoisis do to the number of chromosomes? |
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Definition
| Meiosis halves the number of chromosomes |
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Term
| List all the stages of meoisis? |
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Definition
| Meiosis I
Prophase I
Metaphase I
Anaphase I
Telophase I
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II
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Term
| What does each stage of meiosis 1 do? |
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Definition
Prophase I
Homologous chromosomes pair up and exchange segments
Metaphase I
Homologous chromosome pairs align at random in the equatorial plane
Anaphase I
Homologous chromosomes separate and move to opposite poles
Telophase I
Individual chromosomes gather together at each of the two poles |
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Term
| What are the characteristics of Meiosis I and Prophase I? |
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Definition
| The longest and most complex stage of meiosis |
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Term
| What does homologous chromosomes undergo? |
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Definition
| Synapsis, they pair up along their lengths.
Crossing over occurs. |
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Term
| What happens after Meiosis I? |
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Definition
| A brief interphase----No DNA synthesis occurs |
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Term
| Meiosis II is similar to mitosis, but what are the two main differences? |
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Definition
| 1. Haploid set of chromosomes
2. Sister chromatids are not identical |
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Term
| What are the stages of Meiosis II? |
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Definition
Prophase II
Brief and simple, unlike prophase I
Metaphase II
Spindle fibers bind to both sides of the centromere
Anaphase II
Spindle fibers contract, splitting the centromeres
Sister chromatids move to opposite poles
Telophase II
Nuclear envelope reforms around four sets of daughter chromosomes |
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Term
| Let's compare meiosis and mitosis? |
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Definition
| Meiosis and mitosis have much in common
However, meiosis has two unique features
1. Synapsis
Homologous chromosomes pair all along their lengths in meiosis I
2. Reduction division
There is no chromosome duplication between the two meiotic divisions
This produces haploid gametes |
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Term
| Let's compare meiosis and mitosis? |
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Definition
| Meiosis and mitosis have much in common
However, meiosis has two unique features
1. Synapsis
Homologous chromosomes pair all along their lengths in meiosis I
2. Reduction division
There is no chromosome duplication between the two meiotic divisions
This produces haploid gametes |
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Term
| What are the evolutionary consequences of sex? |
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Definition
| Sexual reproduction increases genetic diversity through three key mechanisms
1. Independent assortment
2. Crossing over
3. Random fertilization |
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Term
| What is Independent assortment? |
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Definition
| In humans, a gamete receives one homologue of each of the 23 chromosomes
Humans have 23 pairs of chromosomes
223 combinations in an egg or sperm
8,388,608 possible kinds of gametes |
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Term
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Definition
| DNA exchanges between maternal and paternal chromatid pairs
This adds even more recombination to independent assortment that occurs later |
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Term
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Definition
| The zygote is formed by the union of two independently-produced gametes
Therefore, the possible combinations in an offspring
8,388,608 X 8,388,608 =
70,368,744,177,664
More than 70 trillion!
And this number does not count crossing-over |
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Term
| Importance of Generating Diversity |
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Definition
| Genetic diversity is the raw material that fuels evolution
And no genetic process generates diversity more quickly than sexual reproduction |
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