1 Biology 11 A. Allen Cytoplasm (cytosol): a cell's inner space cytosol Cytosol: large fluid-filled space (mostly water + proteins that control most of the cell metabolisms): glycolysis, transcription factors, intracellular receptors etc. Plasma membrane Organelles • Nucleus • Protein production machine: the ribosomes • Mitochondria and Chloroplasts • Endoplasmic Reticulum and the Golgi apparatus • Lysosomes and Peroxisomes • Adapted and/or specialized for carrying out one or more vital functions Reminder! Membrane-bound organelles are only found in eukaryotes. Nucleus: a cell's center Function of the nucleus: • Stores the chromosomes (genetic material) Note : Two kinds of genetic material: – deoxyribonucleic acid (DNA) – ribonucleic acid (RNA) • Keeps the DNA molecules separated from metabolic machinery of cytoplasm. • Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells • DNA replication and synthesis of messenger RNA (mRNA). The mRNA is allowed to leave the nucleus. It is read by the ribosomes during protein synthesis. ...Nucleus: a cell's center Nucleolus • Dense mass of material in nucleus • Cluster of DNA and proteins • Subunits must pass through nuclear pores to reach cytoplasm • production of ribosomes in nucleolus
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Biology 11
A. Allen
Cytoplasm (cytosol): a cell's inner space
cytosol
Cytosol: large fluid-filled space (mostly water + proteins that control
most of the cell metabolisms): glycolysis, transcription
factors, intracellular receptors etc.
Plasma
membrane
Organelles
• Nucleus
• Protein production machine: the ribosomes
• Mitochondria and Chloroplasts
• Endoplasmic Reticulum and the Golgi apparatus
• Lysosomes and Peroxisomes
• Adapted and/or specialized for carrying out one or more vital functions
Reminder! Membrane-bound
organelles are only found in
eukaryotes.
Nucleus: a cell's center
Function of the nucleus:
• Stores the chromosomes (genetic material) Note: Two kinds of genetic material:
– deoxyribonucleic acid (DNA)
– ribonucleic acid (RNA)
• Keeps the DNA molecules separated from metabolic machinery of cytoplasm.
• Makes it easier to organize
DNA and to copy it before
parent cells divide into
daughter cells
• DNA replication and
synthesis of messenger
RNA (mRNA). The
mRNA is allowed to leave
the nucleus. It is read by
the ribosomes during
protein synthesis.
...Nucleus: a cell's center Nucleolus
• Dense mass of
material in nucleus
• Cluster of DNA and
proteins
• Subunits must pass
through nuclear pores
to reach cytoplasm
• production of
ribosomes in nucleolus
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• Two outer membranes (lipid bilayers)
• Pores span bilayer and controls what
enters/leaves nucleus.
Nuclear Membrane (Envelope) Chromatin
• Cell’s collection of DNA and associated proteins
• A chromosome is one DNA molecule and its associated proteins
• Appearance changes as cell divides
FUNCTION:
• With the help of tRNA, ribosomes use information in mRNA to assemble proteins
• small semi-spherical, black dots
• some are free in cytoplasm (cytoplasmic ribosomes), others are attached to the ER (ER ribosomes)
Ribosomes
STRUCTURE
• ER is a continuation of the outer nuclear membrane.
• Two types: Smooth and Rough. (Rough ER has ribosomes on it)
• Network of membrane that connects nuclear envelope to the cell
membrane
Endoplasmic Reticulum (ER)
…Endoplasmic Reticulum (ER)
FUNCTION:
• Smooth ER (no ribrosomes): responsible for lipid and membrane
protein modifications)
• Rough ER (has ribosomes on it) responsible for the synthesis of
other proteins). The ribosomes assemble the proteins within the
rough ER. Once assembled, the proteins pinch off the ER and are