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 line up in the middle

  • Anaphase: sister chromatids pulled apart

  • Telophase: new nuclei form, chromosomes relax

  • Cytokinesis: cell splits in two

Checkpoints

  • G1: is DNA okay?

  • G2: did DNA copy right?

  • Metaphase: are chromosomes lined up correctly?

  • Controlled by proteins called cyclins that keep bad cells from dividing

Cancer = Division Gone Wrong

  • Benign tumor = non-cancerous growth

  • Malignant tumor = cancer, spreads to other tissues (metastasis)

  • Caused by mutations in genes that control division (oncogenes, tumor suppressors)

Mitosis vs. Meiosis

  • Mitosis = 1 division, 2 identical cells, used for growth and repair

  • Meiosis = 2 divisions, 4 unique cells, used for reproduction

Chromosome Mutations

  • Duplication = extra section

  • Deletion = missing section

  • Inversion = piece reattaches backward

  • Translocation = piece moves to another chromosome

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

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