guided notes: chromosomes the structure of dna figure 1
TRANSCRIPT
Guided Notes: Chromosomes
The Structure of DNA
What type of macromolecule is DNA? ___________________ ___________________
DNA stands for:
DNA is made up of repeating ______________________________ (the monomer of nucleic
acids!)
1) Where is it found (use figures 1 and 2 to help!) Figure 1
DNA is in the c______________ of
prokaryotes and the
n_________________ of eukaryotes
The nucleus of a human cell contains
30,000 or more g_________ in the form
of DNA, called a c_________________.
2) Function of DNA
The function of DNA is to s_______________ i_________________.
This is essential to life! DNA RNA Proteins (The c____________ d_________ of
molecular biology!
Figure 2: Structure of Chromosomes
These proteins play a key role in how we look and grow-“It’s in your genes!”
A given gene on a chromosome can have alternative forms called alleles. For now, just know
that different alleles of a gene encode the same protein, just slightly different versions of it.
Ex: gene that encodes hemoglobin can be normal allele, or a different allele that produces
abnormal hemoglobin (causes sickle-cell anemia).
DNA is packaged tightly into
pieces called
_____________________
that are visible ONLY during
cell division
Each chromosome includes
several thousand
________________
Most genes contain the
directions to make a
__________________
-Proteins are made up of
______________________
Chromosomes and Chromatids
Chromosomes are only visible during c_______ d______________, when they are tightly
condensed (wound up). Otherwise they are like long strings.
Figure 3: Homologous chromosomes and sister chromatids
Humans have _______ chromosomes.
These chromosomes come in pairs called
h_________________ c__________________
One member of each pair was inherited from
your m____________. The other was inherited
from your f______________.
How many chromosomes do you think the
sperm cell that helped create you had? ________
How many chromosomes did your mom’s egg cell have? _____________
When cells are getting ready to divide, they r____________ their chromosomes (another word
for copy).
MISCONCEPTION ALERT!
When a chromosome has replicated, it is still considered to be ONE chromosome! (Confusing, I
know!) The replicated chromosome is composed of two s__________ c___________. Each sister
chromatid is identical to the sister chromatid it is attached to! When the cell divides (we will discuss in
detail in mitosis unit), the sister chromatids separate and are then considered to be individual
chromosomes.
If a cell has 35 chromosomes, then replicates them as it prepares to divide, it will have
____________ chromosomes and ____________ chromatids. The two cells resulting from the
division will have ____________ chromosomes each.
What is the name of the structure where the sister chromatids are attached to each other?
________________________.
Synthesize your knowledge!
Crystal ponies have 6 chromosomes. That means they have ______ homologous pairs of
chromosomes.
Use a different color for maternal (inherited from mom) and paternal
chromosomes (inherited from dad).
Draw the two resulting cells and their chromosomes (you can depict the
Preparing to divide (Chromosomes have replicated)
chromosomes as still condensed even though in reality they begin to unwind back into long
strings as the cell is pinching in two). Assume the two new cells are NOT YET preparing to
divide so have NOT replicated their chromosomes yet!
Draw a crystal pony cell that is getting ready to divide (I have done
this for you). Imagine that it glitters and sparkles.
Newly formed cells (Chromosomes
have NOT yet replicated)
Make each pair of homologous chromosomes a different size.
Guided Notes: The Cell Cycle
The Cell Cycle
The c_____ c________ describes the life of a
cell from birth to death.
There are three main parts of the cycle:
I_____________ : Normal cell
activities; broken up into 3 parts.
M_____________ : Division of the
nucleus/Separation of the genetic
material into 2 new nuclei.
C_____________ : The division of the
cytoplasm following mitosis.
Interphase
________ phase : Period of cell growth.
Cells can remain in the G1 phase indefinitely, called ______________.
________ phase: Period when DNA replication occurs. Chromosomes replicate and each
chromosome is now composed of two s_____________ c_____________ attached at the
c_____________ (from chromosome notes!).
Once a cell copies its DNA, it prepares to divide.
________ phase: Cell growth and preparation for mitosis.
Mitosis
Mitosis is a form of a_____________ reproduction.
Means only _____ organism is required.
Occurs in response to the body’s need for growth and repair.
Refers to division of the n_____________. (The organelle in eukaryotes that contains DNA)
_____ stages of mitosis: Prophase, Metaphase, Anaphase, Telophase (will learn more about
this soon!).
Cytokinesis
The cell cycle ends with c_____________ : the division of the c____________ (refers broadly
to the stuff in the cell excluding the nucleus)
Overlaps with the latter part of mitosis.
This means one cell has divided into two cells, and those two cells () can continue with
their own independent cell cycles!
Chromosome appearance throughout the Cell cycle (Dr. Williams will fill in with everyone)
Chromosomes are decondensed (long and stringy) during Interphase (G1, S, G2) and do not
condense until mitosis begins! We have been drawing them in their condensed form for convenience
only! Let’s draw the chromosomes throughout the cell cycle using our crystal pony example (cells with
3 pairs of chromosomes).
1. Prophase
- longest phase of mitosis- chroms. become visible- spindle forms- nuclear envelope breaks down
3. Anaphase- sister chromatids move apart to opposite sides
of the cell
4. Telophase- chroms. disperse- 2 nuclear envelopes reform- nucleolus reappears
Cytokinesis- division of cytoplasm- NOT part of mitosis- animal cells: membrane pinches in half- plant cells: cell plate forms- 2 identical daughter cells form
2. Metaphase - chromosomes line up along middle of cell
Mitosis
Parts of Mitosis