BIO 181 Unit 2 Notes

Cell theory

1. the cell is the basic unit/structure and function in organisms

2. all organisms are composed of one or more cells

3. cells arise from pre-existing cells

Why don’t cells just keep getting bigger?

SA:V ratio; larger surface area and less volume allows for better oxygen distrubution

Prokaryotic cells

no nucleus, small, one circular DNA (70S), simple cytoskeleton, divides via binary fission, single-celled

Eukaryotic Cells

Membrane bound nucleus, organelles, bigger, multiple linear DNA (80S), complex cytoskeleton, divides via mitosis

Prokaryotic cell architectural regions

1. cell envelope (plasma membrane covered by a cell wall)

2. cytoplasmic region - houses DNA, ribosomes, and proteins

3. flagella/pili projecting from cells surgaceC

Viruses are acellular

True

What is try of viruses

Have genetic material

A cell discovered has the following characteristics:

• Membrane-bound nucleus

• mitrochondria

• no cell wall

  • multiple linear chromosomes

It is an animal cell

What distinguishes eukaryotes as compared to prokaryotes

compartmentalization

Cell/plasma membrane purpose

membrane that surrounds the cytoplasm of the cells; controls the passage of organic molecules in/out of the cell

Cytoplasm

gel-like inner region between plasma membrane and nuclear envelope

Nucleus

houses Cell’s DNA and directs the synthesis of protein

Ribosomes

Responsible for protein synthesis

Rough endoplasmic reticulum purpose and example

Makes proteins (often found in pancreas producing digestive enzymes)

Endoplasmic reticulum purpose and example

makes lipids (often found in liver detoxifying alcohol/drugs)

Golgi apparatus purpose

Modifies, transports, and packages newly made proteins/lipids in eukaryotic cells

Mitochondria purpose

Provide energy to the eukaryotic cell by converting sugars to ATP

Vesicles

transports materials between organelles within/to the cell membrane

cauole

stores water, nutrients, pigments, waste, and toxins

peroxisomes

used for detoxification and breakdown of fatty acids (prevalent in liver)

Lysosomes

Digestion/recycling of proteins, lipids, polysaccharides, nucleic acids (garbage disposal with acidic interior)

Cytoskeleton

• maintains cell shape

• organizes organelles

• moves materials inside cells

• moves the cell

• separates chromosomes during cell division

Microfilament structure

smallest, formed of actin protein

Microfilament function

cytokenesis, and support just beneath plasma membrane

intermediate filament structure

medium, made of proteins

intermediate filament purpose

resist stretching, holding organelles in place, strengthen cells

microtubules structure

large, composed of tubulin protein

microtubules functions

transport, form cilia + flagella, separate chromosomes during mitosis

Which organelle inside the animal cell is responsible for modifying newly made proteins

Golgi apparatus

Chloroplasts

Carry out photosynthesis, contain chlorophyll (absorbs light)

Cell walls in plants are made of

cellulose

Extra components of plant cells

Cell wall, chloroplasts, plasmodesmata, plastids

Which pair of organelles contain its own DNA and ribosomes?

Chloroplast and mitochondria

If all microtubules are destroyed in a eukaryotic cell, which process is most likely impaired?

Vesicle transport between organelles

why do cells divide?

1. growth

2. repaire/replacement

   1. reproduction

phases of the cell cycle

1. interphase

2. M phase

phases of interphase

G1, S, G2

G1

cell growth

checkpoint: conditions are favorable for cell to enter S phase

G0

subset of G1 where cells rest (do not divide); not all cells enter this state

S

DNA is duplicated
checkpoint: ensures accurate DNA replication and looks for damages

G2

growth, duplication of organelles, cytoplasm skeleton is dismantled

checkpoint: checks if cell is ready to divide (if not, cell cannot enter M phase/division phase)

throughout interphase DNA remains in a loosely packed form called. . .

chromatin

how many chromatids does a human somatic cell have after s-phase?

92

M phase stages

1. division of the nucleus (mitosis, meiosis)

2. cytokenesis

where do mitosis and meiosis occur

Mitosis occurs in body (somatic) cells; meiosis occurs in reproductive organs

what does mitosis produce

mitosis produces 2 genetically identical daughter cells

what does meiosis produce

4 genetically different daughter cells

what happens to chromosomes in mitosis

the number remains the same. this maintains the same genetic composition

what happens to chromosomes in meiosis

chromosome number is reduced by half. this ensures offspring receive the correct number of chromosomes upon fertilization

what is the purpose of mitosis

cells growth, repair, and asexual reproduction

what is the purpose of meiosis

produce sperm and egg cells

stages of mitosis

• prophase

• metaphase

• anaphase

• telophase

prophase

• chromosomes condense and become visible

• nuclear membrane breaks down

• mitotic spindle is assembled in cytosol

• microtubules assemble off the centrosome to prepare for separation

metaphase

the mitotic spindle is fully developed

centrosomes are at opposite poles

chromosomes are aligned at the equatorial place, with sister chromatids on one side of said plate

what is the m checkpoint

it prevents the cell from entering anaphase until every chromosome is correctly attached

anaphase

sister chromatids separate and move toward opposite poles

telophase

chromosomes arrive at opposite ends and decondense

the nuclear envelope reassembles and begins to surround each new set of chromosomes

the mitotic spindle assembly breaks down and the division of the cytoplasm begins via cytokinesis

cytokinesis

the physical separation of the cytoplasmic components into 2 daughter cells (results in 2 genetically identical daughter cells)

binary fission

1. cell copies DNA

2. cells grow

3. the two DNA copies seperate

4. the cell membrane + wall pinch inward

5. the cell splits into two daughter cells

Why do prokaryotes not undergo mitosis? What do they do to reproduce?

they have no nucleus, only circular DNA; Binary fission