The Cell Theory and Characteristics of Cells Part 1

Question 1

What is the purpose of a life cycle?

Answer 1

to develop an organism
from the time of inception to growth to finally maturity when an organism can viably produce another of its kind.

Question 2

Draw, label and explain the phases in a life cycle.

Answer 2

1. Reproduction (Meiosis and fertilization)
   a. The new cells have half the number of chromosomes (n) haploid (1 set of chromosomes – gamete – egg and sperm)
   b. Produces 4 genetically different cells, from the parent cell (One 2n cell makes four n cells)
   c. During fertilization gametes fuse to form a (2n) zygote – the first cell of life
2. Growth and Repair (Mitosis)
   a. Cells maintain the same number of chromosomes (2n) diploid (2 sets of chromosomes – somatic cells)
   b. Produces 2 identical cells from the parent cells

Question 3

Summarize Cell Theory

Answer 3

1. All organisms are composed of cells
2. Cells are the smallest living things
3. Cells arise only from pre-existing cells
   a. In other words, all cells represent a continuous line of descent from the first living cells

Question 4

List the key structures common to all cells.

Answer 4

1. Plasma membrane – surrounds cytoplasm
2. Cytoplasm – helps in metabolic rxns
3. Ribosomes – make proteins
4. DNA (aka chromosomes, plasmids, chromatin) – instructions (in nucleolus)

Question 5

Impact of surface-to-ratio on cell size and biological processes?

Answer 5

• Lower cell size limit is limited by what fits inside
• Upper limit (which depends on the SV ratio) is restricted by rate of diffusion and the time it takes essential molecules to reach cell center
• As a cell increases in size, the volume increases 10x faster than the surface area.
• Need the surface are to carry out exchange of materials with the environment – if volume is too big, cell membrane can’t keep up.

Question 6

Differences between prokaryotic cells and eukaryotic cells

Answer 6

https://images.app.goo.gl/YgCYhJkahABegn91A