Transcript Vocabulary “Inside the Cell”, Chapters 1 and 2

Vocabulary
“Inside the Cell”, Chapters 1 and 2
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Actin
Amino acid
ATP
Carbohydrate
Cell
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Channel protein
Cholesterol
Cytoplasm
Cytoskeleton
Cytosol
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DNA
Electron microscope
Endocytosis
Endoplasmic reticulum
Enzyme
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Eukaryotic cell
Exocytosis
Glycosylation
Golgi
Intermediate filament
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Lipid
Lysosome
Membrane
Micrometer
Microtuble
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Mitochondrion
Nuclear envelope
Nuclear pores
Nucleus
Organ
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Organelle
Prokaryotic cell
Protein
Ribosome
RNA
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RNAi
RNA polymerase
Tissue
Transcription
Translation
Vesicle
Got Energy?
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Food gets broken down into glucose by
digestion.
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Inside the cell, mitochondria take in
glucose and oxygen to generate ATP.
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Waste products of ATP production include
water and carbon dioxide.
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Cells are about 50% efficient in making ATP from
glucose. (The rest of the energy is released as
heat to keep our body warm).
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ATP releases its energy by a phosphate group
breaking off.
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Average cell has 1 billion molecules ATP, that is
used up and replaced every 1 to 2 minutes.
Protein Examples
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Hemoglobin
Amylase, pepsin, lactase (digestion)
Antibodies
Elastin (skin elasticity)
Keratin (hair and nails)
Making Proteins
Transcription
Begins in the nucleus, in the DNA
RNA polymerase breaks apart the 2 strands
of DNA and transcribes it into mRNA
(messenger RNA) (single strand).
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RNA polymerase’s jaws “grip the DNA,”
then split the DNA
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This ½ of the DNA strand is used as a
template to make mRNA.
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Once made, mRNA goes out of the
nucleus to ribosomes either in the
cytoplasm or on the endoplasmic reticulum
where mRNA is used as instructions to
make proteins.
Translation
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mRNA serves as a template to make
a single type of protein.
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mRNA can be used over and over
again to make proteins
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Ribosomes move along the mRNA
and follow its instructions.
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The mRNA codes for different amino acids,
3 at a time, as codons.
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Ribosomes in the cytosol “read” the mRNA
and join the amino acids in the proper order.
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tRNA (transfer RNA) brings the amino acids
from the cytsol to the ribosome.
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Proteins can be made of 1 or more amino
acid chains.
Proteins Made by Ribosomes on
the Endoplasmic Reticulum
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Here, enzymes add specialized chains of
sugar molecules (carbohydrates) to
proteins. This process is known as
glycosylation.
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Glycosylated proteins are “sticky.”
Glycosylated Protein Examples
Fertilized eggs in a woman, to facilitate
implantation in the uterus.
Immune cells, so that they can attach to a
wound.
Red blood cells: the attached sugars
determine blood type
About ½ of all proteins in the body have
attached sugars.
How Do Proteins Get to Where
They Are Needed?
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Proteins are carried in “protective bubbles”
called vesicles.
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Vesicles are made from a small piece of
the endoplasmic reticulum (ER) that
“pinches off” and envelopes the protein
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These vesicles latch on to the Golgi and
then release their proteins inside.
Endocytosis
Allows nutrients and large molecules to enter the
cell.
The cell membrane wraps around the nutrient,
then “pinches off” and forms a vesicle inside the
cell.
To fight infection.
A bacteria is wrapped in a vesicle (endocytosis),
then the vesicle attaches to a lysosome inside
the cell, which breaks down the bacteria.
Exocytosis
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Counterbalances endocytosis.
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Allows cells to dump waste outside the
cell.
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Replaces membrane lost through
endocytosis.
Channel Proteins
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Embedded in the cell membrane.
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Used to transport smaller molecules (e.g. water
or glucose) and charged particles (sodium or
potassium ions) across the membrane.
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Sodium (Na) and potassium (K) ions are
important for muscle contraction (e.g. heart
beating, nerve impulses, digestion, and insulin
release.
Ubiquitin
“you-b-quittin”…not yet!
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One way cells clear out waste is by
attaching a “death tag” to proteins that
they no longer need.
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This tag is known as ubiquitin.
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Proteosome recognizes ubiquitin and
begin digesting the protein.