A lipid bilayer that contains protein channels, enzymes, and receptors
Cholesterol increases membrane fluidity
Cells are negative inside compared to outside; based on Na/K ATPase (3 Na+ out/2 K+ in)
The Na+ gradient that is created is used for co-transport of glucose, proteins, and other molecules
![](https://i0.wp.com/basicmedicalkey.com/wp-content/uploads/2017/06/image00490.gif?w=960)
Desmosomes/hemidesmosomes – adhesion molecules (cell–cell and cell–extracellular matrix, respectively), which anchor cells
Tight junctions – cell–cell occluding junctions; form an impermeable barrier (eg epithelium)
Gap junctions – allow communication between cells (connexin subunits)
G proteins – intramembrane proteins; transduce signal from receptor to response enzyme
Ligand-triggered protein kinase – receptor and response enzyme are a single transmembrane protein
![](https://i0.wp.com/basicmedicalkey.com/wp-content/uploads/2017/06/image00491.gif?w=960)
ABO blood-type antigens – glycolipids on cell membrane
HLA-type antigens – glycoproteins (Gp) on cell membrane
Osmotic equilibrium – water will move from an area of low solute concentration to an area of high solute concentration and approach osmotic equilibrium
CELL CYCLE
G1, S (protein synthesis, chromosomal duplication), G2, M (mitosis, nucleus divides)
G1 most variable, determines cell cycle length
Growth factors affect cell during G1
Cells can also go to G0 (quiescent) from G1
Mitosis
• Prophase – centromere attachment, spindle formation, nucleus disappears
• Metaphase – chromosome alignment
• Anaphase – chromosomes pulled apart
• Telophase – separate nucleus reforms around each set of chromosomes
NUCLEUS, TRANSCRIPTION, AND TRANSLATION
Nucleus – double membrane, outer membrane continuous with rough endoplasmic reticulum
Nucleolus – inside the nucleus, no membrane, ribosomes are made here
Transcription – DNA strand is used as a template by RNA polymerase for synthesis of an mRNA strand
Transcription factors – bind DNA and help the transcription of genes
• Steroid hormone – binds receptor in cytoplasm, then enters nucleus and acts as transcription factor
• Thyroid hormone – binds receptor in nucleus, then acts as a transcription factor
• Other transcription factors – AP-1, NF-κB, STAT, NFAT
Initiation factors – bind RNA polymerase and initiate transcription
![](https://i0.wp.com/basicmedicalkey.com/wp-content/uploads/2017/06/image00492.gif?w=960)
![](https://freepngimg.com/download/social_media/63059-media-icons-telegram-twitter-blog-computer-social.png)
Stay updated, free articles. Join our Telegram channel
![](https://clinicalpub.com/wp-content/uploads/2023/09/256.png)
Full access? Get Clinical Tree
![](https://videdental.com/wp-content/uploads/2023/09/appstore.png)
![](https://videdental.com/wp-content/uploads/2023/09/google-play.png)