Eukaryotic cells pt1

What is a eukaryotic cell?

A cell that contains a nucleus and specialized organelles

What is an organelle?

A specialized structure inside a cell that performs a particular job

What is the main idea linking organelles to disease?

Organelle defect → disrupted cellular process → tissue dysfunction → disease

What does it mean that organelles are interdependent?

Organelles have different jobs but depend on each other to keep the cell functioning

What is the nucleus mainly responsible for?

Storing genetic material → controlling gene expression → transmitting genetic information to daughter cells

What do ribosomes do?

Make proteins

What does the rough ER mainly do?

Helps make → fold → modify → check proteins

What does the smooth ER mainly do?

Drug and toxin metabolism → lipid and steroid synthesis → Ca²⁺ storage and release

What does the Golgi apparatus mainly do?

Modifies → sorts → packages proteins and sends them to their destinations

What is the plasma membrane?

The envelope or boundary surrounding the cell

What is the cytosol?

The jelly-like aqueous part inside the plasma membrane where organelles are suspended

What does aqueous mean?

Water-based

What does the cytosol contain?

Water → organic molecules → dissolved ions

Where are subcellular organelles suspended?

In the cytosol

What is an ion?

An electrically charged particle

What is a metabolic pathway?

A series of chemical reactions occurring inside a cell

Where do many metabolic pathways occur?

In the cytosol

What is an example of a metabolic pathway occurring in the cytosol?

Glycolysis

What is glycolysis?

A metabolic pathway that breaks down glucose

What is the difference between the plasma membrane and cytosol?

Plasma membrane surrounds the cell → cytosol is the jelly-like aqueous material inside it

What is the nucleus?

A membrane-bound organelle that stores genetic material → controls gene expression → transmits genetic information to daughter cells

What does membrane-bound mean?

Surrounded by a membrane

What genetic material is stored in the nucleus?

DNA

What is gene expression?

The use of genetic information in a gene to produce a functional product

How many pairs of chromosomes are found in the human nucleus?

23 pairs

How many chromosomes are in 23 pairs?

46 chromosomes

What is chromatin?

DNA + histone proteins

What are histones?

Proteins associated with DNA that help package it

What does chromatin do?

Packs and regulates DNA

What is the relationship between DNA and histones?

DNA + histone proteins → chromatin

What is the nucleolus?

A region inside the nucleus that is rich in rRNA

What does rRNA stand for?

Ribosomal RNA

What happens in the nucleolus?

rRNA synthesis + ribosome assembly

Why is the nucleolus important?

It produces rRNA and helps assemble ribosomes

What are nuclear pores?

Controlled openings that regulate macromolecular traffic between the nucleus and cytoplasm

What does macromolecular traffic mean?

Movement of large biological molecules between the nucleus and cytoplasm

What surrounds nuclear pores?

Nuclear pore complexes

What does NPC stand for?

Nuclear pore complex

What does the nuclear pore complex do?

Controls movement of molecules through nuclear pores

How does RNA leave the nucleus?

RNA exits the nucleus → passes through nuclear pores → enters the cytoplasm

What is the nuclear lamina?

A supporting structure on the inner part of the nuclear envelope

What does the nuclear lamina do?

Supports nuclear structure and organization

What protein is found in the nuclear lamina?

Lamin protein

What is the relationship between lamin and the nuclear lamina?

Lamin proteins form part of the nuclear lamina and help support the nucleus

What does DNA polymerase do?

Helps with DNA synthesis

What does RNA polymerase do?

Helps with RNA synthesis

What is DNA synthesis?

The production of DNA

What is RNA synthesis?

The production of RNA

What are two examples of nuclear defects discussed in the notes?

Cancer-related nuclear transport defects + laminopathies

What is p53?

A tumor suppressor protein involved in regulating DNA-damage responses

What is a tumor suppressor protein?

A protein that helps prevent damaged cells from continuing to divide when they should not

What DNA-damage response involving p53 is mentioned in the notes?

Cell-cycle arrest

What is cell-cycle arrest?

Stopping the cell from continuing through its division cycle

Why can cell-cycle arrest be useful after DNA damage?

It prevents damaged cells from continuing to proliferate

What does proliferate mean?

Increase in number through cell division

What is a nuclear localization signal?

A signal on a protein that allows it to be recognized for transport into the nucleus

What does NLS stand for?

Nuclear localization signal

What recognizes proteins with a nuclear localization signal?

Nuclear pore complexes

What is an easy way to remember an NLS?

An address label saying send this protein to the nucleus

What can happen if p53 cannot enter the nucleus because nuclear import is defective?

Damaged cells may continue to proliferate

What is the cancer-related chain involving abnormal p53 in the notes?

Defective nuclear import → p53 does not enter nucleus properly → damaged cells can proliferate

What is a laminopathy?

A disease caused by defects or mutations involving lamin proteins

What can mutant lamin protein cause?

A weak or abnormal nuclear envelope

What can happen when lamin proteins are defective?

Weak nuclear envelope → improper cellular proliferation → impaired tissue repair

What condition is given as an example of a lamin-related disorder?

Progeroid syndromes

What is progeria?

An inherited syndrome that produces features of premature aging

What features of progeria are mentioned in the notes?

Loss of subcutaneous fat → reduced muscle development → reduced bone density

What does subcutaneous fat mean?

Fat located underneath the skin

What is the laminopathy disease chain?

Mutant lamin → weak nuclear envelope → abnormal cellular function and tissue repair → disease

What does multinucleated mean?

A cell containing multiple nuclei

Where can multinucleated cells be present according to the notes?

Liver → salivary glands → osteoclasts

Why are skeletal muscle cells multinucleated?

They form through the fusion of cells

What are osteoclasts mentioned as an example of?

Multinucleated cells

Do mature mammalian red blood cells have a nucleus?

No

What happens to the nucleus when mammalian red blood cells mature?

The red blood cell ejects its nucleus

What else do red blood cells lose as they mature?

Other organelles

Why do mature red blood cells eject their nucleus and other organelles?

To create more space for hemoglobin molecules

What is hemoglobin?

The oxygen-carrying protein in red blood cells

How is DNA packed into chromosomes?

DNA is associated with histones

What are chromosomes made from according to the notes?

DNA + histones

What nuclear changes can be seen in cancer according to the notes?

Enlarged nucleus + large nucleoli

Why can cancer cells have large nucleoli?

More ribosomes are synthesized to support cell proliferation

What are ribosomes made of?

rRNA + proteins

What is the main function of ribosomes?

Translate mRNA into protein

What is translation?

The process in which a ribosome uses mRNA to make a protein

What does mRNA provide to a ribosome?

Instructions used to make a protein

What are the two subunits of a eukaryotic ribosome?

60S large subunit + 40S small subunit

What is the complete eukaryotic ribosome?

80S ribosome

What is the ribosome size relationship to memorize?

60S + 40S → 80S ribosome

Where can ribosomes be located?

Free in the cytosol or bound to the ER

What do free ribosomes make?

Many cytosolic proteins + proteins later imported into the nucleus → mitochondria → peroxisomes

What are cytosolic proteins?

Proteins that function in the cytosol

Which organelles can receive proteins produced by free ribosomes according to the notes?

Nucleus → mitochondria → peroxisomes

What types of proteins involve ER-bound ribosomes?

Secretory proteins + proteins incorporated into the cell membrane

What are secretory proteins?

Proteins made to be released from the cell

What examples of secretory proteins are given?

Hormones + enzymes

What is an example of a protein incorporated into the cell membrane?

A receptor

What is a receptor?

A protein that receives or binds a specific signal

Where does translation initially begin for proteins that will enter the ER pathway?

On a free ribosome

What happens first in the ER-targeting pathway?

Translation begins on a free ribosome