Chapter 3: Cell Transport

 CELL TRANSPORT 


Cell Membrane 

The cell membrane is a thin sheet of tissue which covers the insides of a cell and protects it from outside elements. The CM is selectively permeable, meaning that it does not let all materials pass through it! Small, uncharged molecules can pass easily whereas big, charged molecules have a tougher time passing through the membrane


Cell membrane Structure

The cell membrane is made up of phospholipids that are connected by their hydrophobic (dislike water)  tails (tails are what cause the cell membrane to be selectively permeable). 


Passive Transport --> To maintain homeostasis (normal living conditions), usually the number of molecules inside and outside the cell need to balanced. The movement of molecules from a high concentrated area (outside or inside) to a lower concentrated area is known as Passive Transport. 

Passive Transport can happen in two ways: 

Simple diffusion --> Molecules move from high to low concentration across the cell membrane without any outside help of proteins

Facilitated diffusion --> Sometimes molecules are too charged or too big to pass through the cellular membrane and hence need outside help to get past. Facilitated Diffusion is when Molecules move from high to low concentration with the help of either:
  • Carrier proteins (Bind with substance and change shape; slower)
or
  • Channel proteins (Create a hydrophilic tunnel allowing molecule to pass; very selective; faster)






Popular posts from this blog

Meiosis

 MEIOSIS Intro .  In most of the cells in your body, new cells are made through mitosis. This process creates exact copies of cells for growth and repair. But when it comes to reproduction, things work differently.Organisms that reproduce sexually—like humans, dogs, trees, and even insects—use a special type of cell division called meiosis Meiosis I  Prophase I Chromosomes condense Homologous chromosomes pair up to form tetrads Crossing over occurs (exchange of genetic material between chromatids) Spindle fibers form Metaphase I Tetrads align randomly at the middle of the cell This random alignment is called independent assortment Anaphase I Homologous chromosomes are pulled to opposite poles Sister chromatids remain attached Telophase I & Cytokinesis Cell divides into two haploid cells Each chromosome still consists of two sister chromatids Meiosis II 1. Prophase II Chromosomes (still made of sister chromatids) cond...
Read more

Mitosis

MITOSIS Every second, millions of cells in your body are dividing. Some divisions help you grow or heal, while others make the cells needed for reproduction. Let’s break it down. Chromosomes Basics Chromosomes = DNA wrapped around histones, keeping it neat and organized Sister chromatids = identical copies of a chromosome after DNA replication Homologous chromosomes = one from mom, one from dad; same genes but possibly different versions Karyotypes A picture of all your chromosomes, arranged by size and shape 22 pairs of autosomes + 1 pair of sex chromosomes (XX = female, XY = male) Diploid vs. Haploid Diploid (2n) = two sets of chromosomes → body cells Haploid (n) = one set of chromosomes → gametes (sperm/egg) Possible gamete combinations = 2ⁿ (for humans, over 8 million!) The Cell Cycle and Mitosis Interphase: G1 (cell grows), S (DNA copied), G2 (error check) Prophase: chromosomes condense, spindle forms, nucleus breaks down Metaphase: chromosomes l...
Read more

Protein Synthesis

 What is Protein Synthesis Protein synthesis is essential because proteins are the building blocks of life. They perform nearly all functions in a cell, including: - Building and Repairing Tissues – Proteins make up muscles, skin, and organs. - Enzymes – Proteins act as biological catalysts, speeding up chemical reactions. - Hormones – Some proteins (like insulin) regulate body functions. - Transport – Proteins like hemoglobin carry oxygen in the blood. - Defense – Antibodies help fight infections. Since DNA holds the instructions for making proteins, cells need a process to read these instructions and build the correct proteins. That process is protein synthesis. Before we start protein synthesis we must know what are codons: - Codons - 3 letter mRNA sequence which codes for an Amino Acid  - AntiCodon - tRNA sequence complementary to mRNA’s codons, attaches to the mRNA Protein synthesis happens in two main stages: --> Transcription (in the nucleus) --> Translation (in t...
Read more