Ch 25 - Endosymbiosis

Question 1

Endosymbiotic theory

Answer 1

Explains how eukaryotes could have evolved from prokaryotes

A larger cell engulfed smaller cells that evolved into mitochondrion and chloroplasts

Question 2

Examples of endosymbionts

Answer 2

Dinoflagellates, photosynthetic protists

Question 3

Eukaryotic cells contain:

Answer 3

1) nucleus w chromosomes
2) intracellular membranes (RER, SER, Golgi apparatus)
3) mitochondria
4) chloroplasts (plants)

Question 4

How do eukaryotic cells divide?

Answer 4

Mitosis

Question 5

Lynn Margulis

Answer 5

Proposed endosymbiotic theory in 1967

Question 6

Similarities between mitochondrion and bacteria

Answer 6

1) 1-4 um in length
2) surrounded by 2 membranes
3) use O2 to generate ATP
4) have their own DNA
5) grow and divide by binary fission
6) similar genes
7) similar ribosomes
8) similar enzymes

Question 7

What was the reason for the rise of eukaryotes?

Answer 7

Environment change from anaerobic to aerobic

Question 8

What was the reason for the increase in atmospheric O2?

Answer 8

Photosynthesis by cyanobacteria

Question 9

Great oxygenation event

Answer 9

Increase in molecular oxygen 2.3 billion years ago that resulted in mass extinction

Question 10

Main events in evolution of eukaryotic cells

Answer 10

Origin of: flexible cell surface, cytoskeleton, nuclear envelope, phagocytosis, digestive vesicles/vacuoles,

Endosymbiotic acquisition of mitochondria and chloroplasts

Question 11

Flexible cell surface

Answer 11

Prokaryotic cell wall lost, allowing cell to grow larger
As cell size increased, the surface area-to-volume ratio decreased
Infolding can occur, creating internal membranes and more surface area
Allowed endocytosis to develop

Question 12

Origin of the nucleus

Answer 12

Nuclear envelope likely to have arisen from plasma membrane
DNA of prokaryote is attached to plasma membrane
Inward folding of the plasma membrane created a double layer of phospholipids that surrounded the DNA

Question 13

Conversion from extra cellular digestion to intracellular digestion

Answer 13

Phagocytosis - created digestive vesicles and vacuoles

Question 14

a-proteobacterium evolved into….

Answer 14

Mitochondrion

Question 15

Rickettsia

Answer 15

a-proteobacterium
Intracellular parasites in plants and animals
Ticks, fleas, lice
Cause typhus and Rocky Mountain spotted fever

Question 16

Symptoms of Rocky Mountain spotted fever

Answer 16

High fever, severe muscle pain, rash on wrists and ankles

Question 17

Proteobacterium likely fed on ______ and released _______.

Answer 17

Carbon compounds, H+

Question 18

Primitive eukaryotic cells used the H+ to make _____.

Answer 18

ATP

Question 19

What was the initial function of mitochondrion?

Answer 19

To detoxify the increased amounts of O2 in the atmosphere by reducing it to water

Question 20

Cells with mitochondrion are able to carry out ____.

Answer 20

Cellular respiration

Question 21

Respiration yields much more energy from the breakdown of __________, than ________ do.

Answer 21

Carbon compounds, anaerobic pathways

Question 22

Later, a primitive eukaryotic cell incorporated a photosynthetic prokaryote related to modern day __________.

Answer 22

Cyanobacteria

Question 23

Cyanobacteria evolved into ________.

Answer 23

Chloroplasts

Question 24

Advantage of cells containing chloroplasts:

Answer 24

ability to harness energy from the sun to make carbon compounds

Question 25

Why are mitochondrion and chloroplasts incapable of living independently?

Answer 25

Proteins are made in the cytoplasm and THEN imported into organelle