Prophase 2
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Spindle forms and moves the chromosomes towards the middle of the cell.
*Same as prophase in mitosis
Enzymes involved in DNA replication:
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DNA Polymerase
DNA ligase
Helicase
Primase
,3rd line of defense
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Internal adaptive immunity: depends on two types of lymphocytes that
recognize and respond to specific invading pathogens.
Like all blood cells, lymphocytes originate from stem cells in the bone
marrow.
B cells fully develop/specialized in bone marrow.
Immature T cells migrate via the blood to the thymus, a gland in the chest,
where they mature and become specialized.
Both B cells and T cells then make their way to the lymph nodes and other
lymphatic organs and wait to encounter the invader.
Unlike innate immunity defenses, which are ready to fight pathogens at any
time, the adaptive immunity defenses, specifically Band T cells, must be
primed before they attack foreign molecules.
Prophase 1
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Homologous chromosomes pair up and exchange segments. Longest and
most complex phase (90%)
Chromosomes condense.
Synapsis occurs: homologous chromosomes come together to form a
tetrad (2 chromosomes or 4 chromatids). Crossing over occurs ( exchange
corresponding segments). Crossing over rearranges genetic info. Spindle
forms. Homologous pairs move towards center of cell.
Metaphase 1 (Middle)
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, Pairs of homologous chromosomes line up. Shortest phase.
Tetrads align on metaphase plate. **Independent assortment occurs:
1. Orientation of homologous pair to poles is random.
2. Variation
3. Formula: 2n
Sister chromatids of each chromosomes are still attached at their
centromeres ; where they are anchored to spindle tracks.
Variation
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Variation is important to populations as the raw material for natural
selection.
Three sexual sources of genetic variation:
1. Crossing over (prophase 1)
2. Independent assortment (metaphase 1)
3. Random fertilization
Anaphase 1 (Apart)
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Pairs of homologous chromosomes split up. Chromosomes migrate
towards the poles of the cell.
**In contrast to mitosis, sister chromatids migrate as a pair instead of
splitting up.
They are separated not from each other but from their homologous
partners.
Give this one a try later!
Spindle forms and moves the chromosomes towards the middle of the cell.
*Same as prophase in mitosis
Enzymes involved in DNA replication:
Give this one a try later!
DNA Polymerase
DNA ligase
Helicase
Primase
,3rd line of defense
Give this one a try later!
Internal adaptive immunity: depends on two types of lymphocytes that
recognize and respond to specific invading pathogens.
Like all blood cells, lymphocytes originate from stem cells in the bone
marrow.
B cells fully develop/specialized in bone marrow.
Immature T cells migrate via the blood to the thymus, a gland in the chest,
where they mature and become specialized.
Both B cells and T cells then make their way to the lymph nodes and other
lymphatic organs and wait to encounter the invader.
Unlike innate immunity defenses, which are ready to fight pathogens at any
time, the adaptive immunity defenses, specifically Band T cells, must be
primed before they attack foreign molecules.
Prophase 1
Give this one a try later!
Homologous chromosomes pair up and exchange segments. Longest and
most complex phase (90%)
Chromosomes condense.
Synapsis occurs: homologous chromosomes come together to form a
tetrad (2 chromosomes or 4 chromatids). Crossing over occurs ( exchange
corresponding segments). Crossing over rearranges genetic info. Spindle
forms. Homologous pairs move towards center of cell.
Metaphase 1 (Middle)
Give this one a try later!
, Pairs of homologous chromosomes line up. Shortest phase.
Tetrads align on metaphase plate. **Independent assortment occurs:
1. Orientation of homologous pair to poles is random.
2. Variation
3. Formula: 2n
Sister chromatids of each chromosomes are still attached at their
centromeres ; where they are anchored to spindle tracks.
Variation
Give this one a try later!
Variation is important to populations as the raw material for natural
selection.
Three sexual sources of genetic variation:
1. Crossing over (prophase 1)
2. Independent assortment (metaphase 1)
3. Random fertilization
Anaphase 1 (Apart)
Give this one a try later!
Pairs of homologous chromosomes split up. Chromosomes migrate
towards the poles of the cell.
**In contrast to mitosis, sister chromatids migrate as a pair instead of
splitting up.
They are separated not from each other but from their homologous
partners.
