Unit 3: Information Flow
Learning Objectives
1. Determine the relationship between DNA, chromatin, chromosomes, and
chromatids
o DNA is one of the main components of chromatin and contains genetic
information.
o Chromatin is the DNA and protein complex found in eukaryotic cells. DNA is
wrapped around proteins called histones at regular intervals.
o A Chromosome is a single piece of chromatin OR a replicated set of chromatin
pieces that remain attached at the centromere (center of chromosome – black dot)
– so it is called a chromosome both originally and also after replication
o Sister chromatids are each one of the replicated pieces of chromatin within a
chromosome
2. Describe the cell cycle and contrast mitosis with DNA replication and cytokinesis
o The cell cycle is the event sequence during which a eukaryotic cell replicates
DNA and divides. Lengths of gap phases vary.
, o Mitosis is the division of the nucleus that results in two identical daughter nuclei.
o Cytokinesis is the division of the cytoplasm that results in two daughter cells
(usually occurs in conjunction with mitosis or meiosis).
o Interphase (which includes DNA replication) and cytokinesis are NOT part of
mitosis.
3. Recall functions of mitosis and cytokinesis
o The first portion of the mitotic phase is called karyokinesis (mitosis), or nuclear
division. The second portion of the mitotic phase, called cytokinesis, is the
physical separation of the cytoplasmic components into the two daughter cells.
The function of mitosis is to divide the nucleus of the cell, and the function of
cytokinesis is to divide the cell itself. Remember that mitosis is division of
somatic cells, so just a piece of the body.
4. Recognize the major event for each phase of mitosis and explain how cytokinesis
differs between plant and animal cells
o Prophase: chromosomes condense (light blue jumbled mess to darker diploids)
o Prometaphase: nuclear envelope disintegrates (you see the nucleus slowly
disappearing and the chromosomes spreading out into the entire cell)
o Metaphase: chromosomes move to middle
, o Anaphase: centromeres split and chromosomes are pulled to opposite ends
o Telophase: new nuclear envelopes will form around chromosomes. This is the end
of mitosis (now have 2 identical daughter nuclei within a single cell)
o Cytokinesis: the process that goes along with mitosis, usually starts toward the
end of mitosis (near anaphase) and ends by the time mitosis ends. Cytoplasm
divides into two daughter cells.
▪ Plant cells: builds a new cell wall (cell plate) AND cell membrane
between the two nuclei and separates that way
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