Number:
Science: Nucleus, Ribosomes, ER
Name:
#6.3
Date:
HR:
Objective: I can compare and contrast the function of the nucleus, ribosomes, and
endoplasmic reticulum.
DO NOW
1. A rock is pushed deep underground in an area where mountain building is occurring and
undergoes the following processes.
First, the rock experiences high pressure that causes its minerals to align
themselves in bands.
Second, the rock is pushed further underground and completely melts, then erupts
from a volcano and hardens.
Third, the rock is broken down by wind and water into small particles, which flow
into a river and get compressed into rock.
Which order correctly shows this progression of rock types?
A. igneous  metamorphic  sedimentary
B. metamorphic  igneous  sedimentary
C. metamorphic  sedimentary  igneous
D. sedimentary  igneous  metamorphic
2. Which of the following provides evidence for plate tectonics?
A. Coriolis effect
B. ocean currents
C. atmospheric temperature variations
D. sea-floor spreading
HOMEWORK REVIEW
1. Which type of rock is formed from weathering, erosion, deposition, compaction, and
cementation?
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2. What are two differences between Earth’s inner and outer core?
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3. What happens to lithospheric plates at a convergent boundary?
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4. Newton’s third law of motion states that every action force is accompanied by what?
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REVIEW FROM YESTERDAY
What is the function for each of the following cell parts?
Cell Membrane ______________________________________________________________________
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Cytoplasm ____________________________________________________________________________
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Organelle ____________________________________________________________________________
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DNA ______________________________________________________________________________
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Objective: I can compare and contrast the function of the nucleus, ribosomes,
mitochondria and endoplasmic reticulum.
Two Kinds of Cells
All cells have ________________________________, ___________________________,
_____________________, and ________________. But there are two basic types of cells—
cells without a nucleus and cells with a nucleus. Cells with no nucleus are prokaryotic
(proh KAR ee AHT ik) cells. Cells that have a nucleus are eukaryotic (yoo KAR ee AHT
ik) cells. Prokaryotic cells are further classified into two groups: bacteria (bak TIR ee uh)
and archaea (AHR kee uh).
Eukaryotic Cells and Eukaryotes
Eukaryotic cells are the largest cells. Most eukaryotic cells are still microscopic, but they
are about 10 times larger than most bacterial cells. A typical eukaryotic cell is shown
below.
All living things that are not bacteria or archaea are made of one or more eukaryotic cells.
Organisms made of eukaryotic cells are called eukaryotes. Many eukaryotes are
multicellular. Multicellular means “many cells.” Multicellular organisms are usually larger than
single-cell organisms. So, most organisms you see with your naked eye are eukaryotes.
There are many types of eukaryotes. Animals, including humans, are eukaryotes. So are
plants.
1. What is the difference between prokaryotic and eukaryotic organisms?
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Eukaryotic Cells
Even though most cells are small, cells are still complex. A
eukaryotic cell has many parts that help the cell stay alive.
Similarities:
Plant cells and animal cells are two types of eukaryotic cells.
These two types of cells have many cell parts in common. But
plant cells and animal cells also have cell parts that are different.
Look at the diagrams below. List similarities and differences you
see between plant and animal cells.
Differences:
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Nucleus
The nucleus is a large organelle in a eukaryotic cell that directs all cell activities and is
separated from the cytoplasm by a membrane. Materials enter and leave the nucleus
through openings in this membrane. The nucleus contains the instructions for everything the
cell does. These instructions are found on DNA, the chemical structure that contains the
code for the cell’s structure and activities.
The nucleus of many cells contains a dark area called the nucleolus, where a cell begins
to make its ribosomes.
1. What is the function of the nucleus in a eukaryotic cell?
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2. What is the nucleolus and what does it do?
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Ribosomes
One substance that takes part in nearly every cell activity is protein. Proteins are part of
cell membranes, and other proteins are needed for chemical reactions that take place in
the cytoplasm. Organelles that make proteins are called ribosomes. Ribosomes are some of
the smallest of all organelles, and there are more ribosomes in a cell that there are any
other organelles. Some ribosomes float freely in the cytoplasm. Others are attached to
membranes. Unlike most organelles, ribosomes are not covered by a membrane.
3. What is unique about ribosomes and what is their function?
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Endoplasmic Reticulum
Many chemical reactions take place in a cell. Many of these reactions happen on or in the
endoplasmic reticulum (EN doh PLAZ mik ri TIK yuh luhm). The endoplasmic reticulum, or
ER, is a system of folded membranes in which proteins and other materials are processed
and transported inside the cell. The ER is shown below.
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The ER is part of the internal delivery system of the cell. Its folded membrane contains
many tubes and passageways. Substances move through the ER to different places in the
cell.
Endoplasmic reticulum is either rough ER or smooth ER. The part of the ER covered in
ribosomes is rough ER. Rough ER is usually found near the nucleus. Ribosomes on rough
ER make many of the cell’s proteins. The ER delivers these proteins throughout the cell.
ER that lacks ribosomes is smooth ER. The functions of smooth ER include making lipids
and breaking down toxic materials that could damage the cell.
3. Describe the function of the endoplasmic reticulum.
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4. Compare and contrast the function of the nucleus and ribosomes.
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5. Describe how the nucleus, ribosomes, and endoplasmic reticulum work together to
help a cell function.
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