Cell size
1 / 7

Cell Size - PowerPoint PPT Presentation

  • Uploaded on

Cell Size. Unit 3 Part 2 – The Cell. Why are cells small?. Why cells are small? Diffusion limits cell size DNA limits the cell size. Surface area-volume ratio. Diffusion Limits Cell Size.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about ' Cell Size' - anastacia-manella

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Cell size

Cell Size

Unit 3 Part 2 – The Cell

Why are cells small
Why are cells small?

  • Why cells are small?

    • Diffusion limits cell size

    • DNA limits the cell size.

    • Surface area-volume ratio

Diffusion limits cell size
Diffusion Limits Cell Size

  • Diffusion is fast and efficient over short distances, it becomes slow and inefficient over larger distances.

    • Small cell

      • good diffusion

    • Big cell

      • bad diffusion

  • Speed of Diffusion

    • An organelle in the center of a 20μm diameter cell receives supplies a fraction of a second after it enters the cell.

    • An organelle in the center of a 20 cm diameter cell would have to wait months before receiving supplies that enter the cell.

Dna limits cell size
DNA Limits Cell Size

  • The DNA tells the cell which proteins to be made.

  • Not enough protein the cell will die. Take time for protein to be produced.

  • As cells increase in size, no extra DNA is made

Surface area volume ratio
Surface Area-Volume Ratio

  • As cell size increases, volume increases much faster than surface area.

    • A 1mm cube has a surface area of 6mm2 and a volume of 1mm3. A 2mm cube has a surface area of 24mm2 and a volume of 8mm3

  • The larger the volume of the cell, the smaller the surface area gets.

As a organism grows can the cells get bigger
As a organism grows, can the cells get bigger?

  • Before a cell gets too large, it divides into two “daughter” cells.

  • Before cell division takes place, the cell must replicate all of its DNA.

  • The cell then divides and solves the problem of the cell becoming too large.

Why must cells divide
Why must cells divide?

Cell size vs. surface area must remain at an efficient ratio

Growth - bigger organism needs more cells

Repair - regeneration of skin, blood & bone etc.

Reproduction - asexual vs sexual