How to tell the difference between mitosis and meiosis

academics biology meiosis mitosis

If you’ve ever taken a biology class, you’ve most likely come across the concept of the cell cycle. Put simply, the cell cycle is the growth of cells, the replication of DNA, and the subsequent division of DNA, organelles, and cytoplasm that creates new cells. For eukaryotes, cell division is an essential part of both growth and reproduction. However, autosomal cells (cells of the body) and gametocytes (germ cells, or reproductive cells) divide in two different ways. We call these processes mitosis and meiosis, respectively.

It’s not always easy to remember what distinguishes each process, so we’ll break down the key differences here. But before we get into the details, let’s understand some basics:

Autosomal cells are diploid (2n). This means that they have 2 versions of each chromosome–one that came from mom, and one from dad. The human genome has 23 chromosomes, so each autosomal cell carries 46 chromosomes in total.

Gametes (sperm and egg cells) are haploid (n). This means that they have only 1 version of each chromosome. Each gamete carries 23 chromosomes in total. When 2 gametes combine during fertilization, the resulting zygote is diploid (2n), and has 46 chromosomes.

Now let’s talk about mitosis: the process of making more diploid (2n) body cells.

In the G1 phase of the cell cycle, the cell grows in size and creates more organelles.

In the S phase, the cell replicates all of its DNA. This does NOT mean that there are now 92 chromosomes, it just means that all 46 chromosomes have 2x the amount of normal DNA.

In the G2 phase, the cell once again grows. It also checks to make sure that a) it’s big enough to divide, and b) no mistakes have been made in DNA replication.

In the M phase, or mitosis and cytokinesis, the cell finally divides. It begins with prophase.

 

In anaphase I, the homologous pairs separate. Unlike in anaphase of mitosis, the centromeres of each individual chromosome do not split and separate sister chromatids; instead the entire chromosome moves toward one end of the cell, away from its partner.

In telophase I, much like telophase of mitosis, nuclear membranes reform around each new nucleus. The key difference is that once cytokinesis pinches off the two new cells, both are now HAPLOID (n). They contain only 23 chromosomes, but each consists of two chromatids. These chromatids would be identical, except the crossing over in prophase I has given them random portions of DNA from the homologous chromosome now in the OTHER cell.

Comments

topicTopics
academics study skills MCAT medical school admissions SAT expository writing college admissions English MD/PhD admissions GMAT LSAT GRE writing strategy chemistry physics math biology ACT graduate admissions language learning law school admissions test anxiety interview prep MBA admissions academic advice premed homework help personal statements AP exams creative writing MD career advice study schedules summer activities Common Application history test prep philosophy computer science secondary applications organic chemistry economics supplements PSAT admissions coaching grammar law statistics & probability psychology ESL research 1L CARS SSAT covid-19 legal studies logic games reading comprehension dental admissions mathematics USMLE Spanish calculus engineering parents Latin verbal reasoning DAT excel mentorship political science French Linguistics Tutoring Approaches academic integrity case coaching chinese AMCAS DO MBA coursework PhD admissions Social Advocacy admissions advice biochemistry classics diversity statement genetics geometry kinematics medical school mental health quantitative reasoning skills time management Anki English literature IB exams ISEE MD/PhD programs algebra algorithms art history artificial intelligence astrophysics athletics business business skills careers cold emails data science internships letters of recommendation poetry presentations resume science social sciences software engineering study abroad tech industry trigonometry work and activities 2L 3L Academic Interest DMD EMT FlexMed Fourier Series Greek Health Professional Shortage Area Italian Lagrange multipliers London MD vs PhD MMI Montessori National Health Service Corps Pythagorean Theorem Python STEM Sentence Correction Step 2 TMDSAS Zoom acids and bases amino acids analysis essay architecture argumentative writing brain teaser campus visits cantonese capacitors capital markets cell biology central limit theorem chemical engineering chess chromatography class participation climate change clinical experience community service constitutional law consulting cover letters curriculum demonstrated interest dental school distance learning electricity and magnetism enrichment european history executive function finance first generation student freewriting fun facts functions gap year genomics harmonics health policy history of medicine history of science hybrid vehicles hydrophobic effect ideal gas law induction information sessions institutional actions integrated reasoning intern international students investing investment banking lab reports logic mandarin chinese mba mechanical engineering medical physics meiosis microeconomics mitosis music music theory neurology neuroscience office hours operating systems organization pedagogy phrase structure rules plagiarism pre-dental proofs pseudocode psych/soc quantum mechanics resistors resonance revising scholarships school selection simple linear regression slide decks sociology software stem cells stereochemistry study spots synthesis teaching technical interviews transfer typology units virtual interviews writer's block writing circles