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38 Cards in this Set
- Front
- Back
Structure of a chromosome
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Rod-shaped structure that contains supercoiled DNA (double helix)
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Before the cell splits:
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DNA is copied and the rod-like structures become 'X'-shaped
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Sister Chromatids
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The two parts of the 'X'-shaped chromosomes- identical
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In somatic (body) cells, chromosomes occur in [...]? Where does each come from?
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[pairs]
One pair from mom, one from dad Think <DIPLOID> |
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These pairs are HOMOLOGOUS, meaning:
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They have similar but not identical genes
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In sex cells, chromosomes occur [...].
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Individually
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<HAPLOID>
The information comes as [...] from... |
The information comes as a half set of info from EITHER mom OR dad- but not both
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Why is it important that information for Haploids comes this way?
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Fertilization joins haploid cells together to create the first unique haploid cell
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Species have a [...] number of chromosomes in the somatic cells.
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[Specific]
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What is the relationship between the number of chromosomes and complexity?
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No relation. Number of chromosomes is NOT an indication of complexity.
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Autosomes:
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Chromosomes that do not contain genes relating to gender.
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Sex Chromosomes
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Last pair determines gender.
These contain genes other than gender, however. |
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XX
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Female
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XY
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Male
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Gametes:
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Sex cells- Egg + Sperm
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Characteristics of sex cells
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Sex cells are:
Haploid and unique (unique combinations of genes) |
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Gametes are formed through the process of..
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Meiosis
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What is the location of Meiosis?
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Reproductive organs: Ovaries and Testes
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What is the function of Meiosis?
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Meiosis is a series of two nuclear cell divisions that results in unique haploid cells.
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Name the four phases of Meiosis 1.
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Prophase
Anaphase Metaphase Telophase (Cytokinesis) |
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Name the four phases of Meiosis 2.
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Prophase 2
Anaphase 2 Metaphase 2 Telophase 2 (cytokinesis) |
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What are the differences between Meiosis 1 and 2?
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The stage of "Crossing-Over" and Independent Assortment.
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"Crossing Over" occurs during which phase?
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Prophase 1
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What happens during "Crossing Over"?
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Homologous chromosomes swap portions of chromatids creating four unique sets of genes on the chromatids.
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What is the significance of "Crossing Over"?
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The four unique sets of genes on the chromatids guarantess genetic diversity.
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When does independent assortment occur?
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During Anaphase 1 and 2.
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What happens during independent assortment?
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The chromatids segregate any influence by chromosome pairs.
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What is the significance of independent assortment?
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Guarantees genetic diversity.
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Why is genetic diversity so important?
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Genetic diversity is important because a whole species could die out, all of them being susceptible to a disease/weakness without "crossing over".
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Oogenesis:
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Formation of eggs (ootids) in the ovaries.
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What does oogenesis result in?
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One viable egg, three polar bodies.
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What happens to the three polar bodies? Why?
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The egg is much larger- the three polar bodies are tiny, and dissolve.
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Oocites:
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Egg follicles
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What happens to the oocites when mature?
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At puberty, the oocites will be released once a month for approximately forty years until menopause.
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Spermatogenesis:
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The formation of sperm cells (spermatids) in the testes.
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Spermatogenesis results in:
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Spermatogenesis results in four viable sperm cells
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This process begins at [...] and continues until the age of [...].
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[puberty]/[70]
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This means that approximately how many sperm cells are made per day?
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Thousands
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