Analytic rubric: version March 9, 2015:
1. same genes (explicit) : answers indicating explicitly that the two cell type have the same
genome/genetic/genes/DNA composition. Examples:
a. “although they have the same genes different genes are expressed by the cells to do
their different function”
b. “Both eye cells and heart cells have the same genes, however depending on what
signals are sent to the promoters in each, determines what genes are turned on causing
the cells to have different functions. Which is how they are different.”
c. “The DNA material would be the same but the expression of that DNA would be
different in the eye location and heart location.”
2. same genes (implicit): although same DNA has not being said explicitly, the answer clearly shows
the student knows the two cells have the same DNA. Examples:
a. Simply saying “different gene expression” – in instances where students discuss this
without saying this explicitly it does not need to be scored as implicit, for example –
"The human eye and heart cells are different because the RNA codes for different
proteins proteins that are expressed differently to make a heart or an eye cell."
b. Referring to the fact the in two cells “different promoters are active”
c. “A human eye will have different genes being expressed than a heart cell. These genes
are expressed differently due to the promoter, which is similar to a light switch since it
is what turns the gene on and off. This will lead to different protein tertiary structures
which leads to the function of the protein. The tertiary structure of a human eye cell
and a heart cell will be different.”
d. “Human eye and heart cells are differentiated cell due to the difference in the locations
of their promoters. Since the promoters are in different areas in cell, different genes are
activated ultimately creating different cells with different functions.”
e. “Human heart cells develop differently than eye cells because the genetic code in the
heart cells have different genes triggered to create muscle cells that make up the heart.
3. different DNA/ genes/genome (explicit)
a. “Human heart cells and eye cells are different because the two have different genes
that code for different sequences of DNA. The different sequences of DNA allow the
cells to have varied functions within the body like heart or eye function respectively.”
b. “Human eye and heart cells are different because of the DNA base sequence of
proteins. Since they both have different sequences this means they have different
functions.”
c. I think one main thing would be because one is an eye cell and one is a heart cell they
would have different genes. I would also think that the heart cells would be stronger
than the eye cells because there is more blood flowing to the heart.
d. “The cells are similar the heart cell carries more information than an eye cell so the
heart cell has more DNA RNA and amino acids.” Note that in this case, different genes
is not explicit but we all scored this answer in past as different genes
Differential gene expression and different genes are mutually exclusive
NOTE: Bins 1, 2, and 3 are mutually exclusive
4. different gene expression: Saying different expression or that genes are used in different ways
(when the question implies that the two cells have the same DNA). May also refer to the
production of different mRNA by the two type of cells (again, if same DNA is implied in the
answer). Examples
a. “Human eye cells and heart cells in an individual have the same DNA, but they have
different active genes. These genes have the information to synthesize different
proteins, and proteins are the "workers" of the cell, determining its form and function.”
b. “Hearts and eyes have very different functions and therefor require very different
protein to be synthesized around them.” Note that this answer wouldn’t fit in
physiology, because is not giving an example of function.
c. "They also differ in how they use the DNA code."
Differential gene expression and different genes are mutually exclusive
5. (stem) cell differentiation or specialization:
a. “The differences between human eye and heart cell starts from the process of stem cell
differentiation. The stem cell differentiate in the cell cycle. (…)”
b. “Stem cells express proteins on the plasma membrane that act as receptors to signals.
Each cell receives different signals that turn on and off specific proteins, causing a
specific function for that cell. Therefore, the different signals that the cell receives
results in different functions for those cells, including the human eye cell and the heart
cell.”
c. “Well, cells are grown and reproduce by mitosis and different because of
differentiation. (…)”
d. "However, it is the specialization of their function given to them by originating stem
cells that make them different ."
6. physiology and/or function : it has to cite a specific function or physiological role for the two
cells. Can also include the types of cells in each tissue. Examples:
a. human heart cells are made out of red muscle cells which are designed to sustain long
continuous movement ex your heart beating. your eye cells are made out of white
muscle cells which are designed for quick rapid movement ex. blinking.”
b. “The eyes contain cells called rods and cones. The brain contains nerve cells”
c. “The both are different functions in the human body so the make up of them are any
different the function of the eye cell is to allow you to see colors and objects while the
heart cells make up the hear wall.”
7. Unclear/incorrect ideas: Unclear are answers that despite containing correct information, rater
cannot tell if the student knows the genetic difference between the two cells asked in the
question. Answers may have information about physiology, development/differentiation but
any reference to genes addresses neither whether the two cells have same/different genes nor
how genes are expressed. Incorrect are answers that either don’t address the question, are
irrelevant or wrong. Examples:
a. “The DNA codes for different cells”
b. “in their function, they express different phenotypes which gives them different
functions”
c. “Heart cells are made of different proteins from eye cells and therefore carry out
completely different functions. These proteins are expressed and created through
genes”
d. Cells have different signals to turn different things on and off. This activates different
things making heart cells and eye cells different.” No content
e. “the diferrence between human heart cell and eye cells is that human heart cell is one
of the members of the body within which cells do not regenerate at all. However the
eye cells can regenerate.” No content, incorrect information
f. “eye cells are in the eye! and heart cells are in the heart1” Note that this answer
doesn’t fit in physiology, because is not giving an example of function.
g. “Brain cells are nerve cells that are activated by genes specific to the brain. heart cells
are muscle cells and are activated by genes specific to the heart.” Cell are not activated
by genes
h. “The different cells in the body code for different functions when made and processed
resulting in some of the cells being turned into heart cells and some eye depending on
what cells are needed” Cells don’t code for functions nor are not turned off/on in
tissues