A2.1 Origin of Cells + A2.2 Cell Structure + A2.3 Viruses

Viruses are _____ ______ _____

Viruses are obligate intracellular parasites

Viruses are _____ (smaller/bigger) than bacteria

Viruses are smaller than bacteria

True or false: viruses only have RNA as genetic material

False: viruses only have RNA as genetic material

(Viruses may have DNA or RNA)

Viruses have a protective protein coat, known as a _____, surrounding the genetic material

Viruses have a protective protein coat, known as a capsid, surrounding the genetic material

True or false: viruses have cytoplasm

False: viruses have cytoplasm

(Viruses do not have cytoplasm.)

True or false: viruses have a cell wall

False: viruses have a cell wall

[Viruses do not have a cell wall (nor do they have cells)]

Icosahedral virus shape

20 faces. Look up pic

helical virus shape

rod shaped

Some viruses are _____ in the host cell membrane, while others are not.

Some viruses are enveloped in the host cell membrane, while others are not.

Draw the lytic cycle, labeling the steps.

Refer to slides

In the bacteriophage lambda lytic cycle, ______ enzymes produced by the virus degrade the bacterial chromosomes, allowing the bacteriophage to hijack the cell's transcription and translation mechnism

In the bacteriophage lambda lytic cycle, endonuclease enzymes produced by the virus degrade the bacterial chromosomes, allowing the bacteriophage to hijack the cell's transcription and translation mechnism

In the lytic cycle of bacteriophage lambda, the cell lyses due to ____ being produced, which damages the E. coli cell wall.

In the lytic cycle of bacteriophage lambda, the cell lyses due to enzymes being produced, which damages the E. coli cell wall.

Draw the lysogenic cycle.

Refer to slides

A _____ is the viral DNA of a virus that has integrated itself into the bacterial choromsome and is able to produce phages if activated

A prophage is the viral DNA of a virus that has integrated itself into the bacterial choromsome and is able to produce phages if activated

The infected bacterium in the lysogenic cycel is known as a _____.

The infected bacterium in the lysogenic cycel is known as a lysogen.

True or false: a lysogen may be triggered to enter the lytic cycle.

True: a lysogen may be triggered to enter the lytic cycle.

The similarities between viruses could result from _____ _____, as similar adaptations are required for being obligate parasites.

The similarities between viruses could result from convergent evolution, as similar adaptations are required for being obligate parasites.

The ____ _____ Hypothesis proposes that viruses existed before cells, as they are much simpler than cells. The ancestors of modern viruses could have provided the raw material for the first cells.

The Virus First Hypothesis proposes that viruses existed before cells, as they are much simpler than cells. The ancestors of modern viruses could have provided the raw material for the first cells.

Virus First Hypothesis

Strength:

Weakness:

Virus First Hypothesis

Strength: Virus genomes have genes that are not present in cells

Weakness: All modern viruses can only replicate using cells, suggesting that viruses could not have existed before cells.

The _____ Hypothesis suggests viruses evolved from sections of DNA or RNA that escaped from cells.

The Escape Hypothesis suggests viruses evolved from sections of DNA or RNA that escaped from cells.

Escape Hypothesis

Strength:

Weakness:

Escape Hypothesis

Strength: Modern bacterial cells exchange genetic material, suggesting a possible escape mechanism. This would also explain the diversity of viruses if genetic material escaped many times.

Weakness: Most of the genes and proteins found in viruses are not found in cells.

The _____ Hypothesis suggests viruses were once small cells that parasitized larger cells. The genes not required for their parasitism have been lost over time.

The Regressive Hypothesis suggests viruses were once small cells that parasitized larger cells. The genes not required for their parasitism have been lost over time.

Regressive Hypothesis

Strength:

Weakness:

Regressive Hypothesis

Strength: The existence of giant viruses which have similar genetic material to parasitic bacteria

Weakness: The smallest cellular parasites do not resemble viruses in any way

_____ are any substance that causes the immune system to produce antibodies

antigens are any substance that causes the immune system to produce antibodies

Mutation of the viral _____ can cause the immune system to no longer recognize the virus.

Mutation of the viral antigen can cause the immune system to no longer recognize the virus.

Immune systems select ____ (for/against) viruses that have not mutated as they recognise the antigens on the capsid surface.

Immune systems select ____ (for/against) mutated versions of the virus, as they do not recognise the antigens on the capsid surface.

Immune systems select against viruses that have not mutated as they recognise the antigens on the capsid surface.

Immune systems select for mutated versions of the virus, as they do not recognise the antigens on the capsid surface.

The influenza virus is a(n) ____ (RNA/DNA) virus that can mutate through antigenic drift and antigenic shift.

The influenza virus is an RNA virus that can mutate through antigenic drift and antigenic shift.

Antigenic shift and drift cause a shape change to the __ and __ surface proteins of the influenza virus.

Antigenic shift and drift cause a shape change to the HA and NA surface proteins of the influenza virus.

A virus is an _____ _____ ______

A virus is an obligate intracellular parasite

Antigenic ____ is a gradual process caused by the gradual accumulation of mutations in the genes coding for antigens. This causes the shape to change, resulting in new strains of the virus.

Antigenic drift is a gradual process caused by the gradual accumulation of mutations in the genes coding for antigens. This causes the shape to change, resulting in new strains of the virus.

Antigenic ____ is an abrupt change to the antigens of a virus, caused by an organism being infected with two different strains of the virus. When the viruses are being synthesized by cells, the genetic material from the two virus strains can ______, resulting in combinations of antigens not recognised by the immune system. May result in a pandemic.

shift; recombine

Antigenic shift is an abrupt change to the antigens of a virus, caused by an organism being infected with two different strains of the virus. When the viruses are being synthesized by cells, the genetic material from the two virus strains can recombine, resulting in combinations of antigens not recognised by the immune system. May result in a pandemic.

The three parts of cell theory:

1.

2.

3.

The three parts of cell theory:

1. All living things are composed of cells

2. Cells are the basic units of structure and function

3. Cells come from preexisting cells

Practice labeling parts of a microscope

Magnification formula

Magnification = ?

Magnification = measured length / actual length

3 mm = x µm

3 mm = 3000 or 3x10^3

Convert 500 mm to nm.

500 mm = 500000000 or 5x10^8 nm

Using an eyepiece graticule, you determine that a cell is 5µm long. Convert this to mm and nm.

5µm = .005 mm = 5000 nm

If a red blood cell has a diameter of 8µm and a student shows it with a diameter of 40mm in a drawing, what is the magnification of the drawing?

Magnification = measured length / actual length= 40 mm / 8µm = 40x10^3 µm / 8µm = 5000

What are the units for magnification?

There are no units for magnification.

The scale bar's measured length is 20mm. The actual length of the scale bar is .4nm. Magnification = ?

= 20mm / .4nm= 20,000,000nm / .4 nmMagnification = 50,000,000

____ ______ microscopy allows scientists to view proteins and other biomolecules which do not readily crystalise

Cryogenic electron microscopy allows scientists to view proteins and other biomolecules which do not readily crystalise

_____ _____ ______ microscopy is a technique used to exam the ultrastructure of rapidly frozen biological samples, such as plasma membranes

Freeze Fracture Electron Microscopy is a technique used to exam the ultrastructure of rapidly frozen biological samples, such as plasma membranes.

______ is a technique used to visualize a specific protein or antigen in cells or tisue by binding a specific antibody chemically attached to a fluorescent dye.

Immunofluorescence is a technique used to visualize a specific protein or antigen in cells or tisue by binding a specific antibody chemically attached to a fluorescent dye.

_____ stains can be used to detect molecules at low concentrations and in living tissue.

Fluorescent stains can be used to detect molecules at low concentrations and in living tissue.

Memorize the tables in the cell structure slides.

Phospholipid plasma membrane: in prokaryotic, eukaryotic, or both?

Phospholipid plasma membrane: in both

Cytoplasm where most metabolism occurs: in prokaryotic, eukaryotic, or both?

Cytoplasm where most metabolism occurs: in both

Chloroplasts: in eukaryotic, prokaryotic, or both?

Chloroplasts: in eukaryotic

DNA as the genetic material: in prokaryotic, eukaryotic, or both?

DNA as the genetic material: in both

Nucleus: in eukaryotes, prokaryotes, or both?

Nucleus: in eukaryotes

Ribosomes for protein synthesis: in eukaryotes, prokaryotes, or both?

Ribosomes for protein synthesis: in both

Prokaryotes: small 70S ribosomes

Eukaryotes: large 80S ribosomes

The ____ ____ controls what enters and exits the cell. It is composed of _____.

The plasma membrane controls what enters and exits the cell. It is composed of phospholipids.

Most of the metabolism that occurs in the cell occurs in the ______. It is mostly composed of water.

Most of the metabolism that occurs in the cell occurs in the cytoplasm. It is mostly composed of water.

Ribosomes are responsible for _____ synthesis.

Ribosomes are responsible for protein synthesis.

Chromosomes associated with histone proteins are located in the _____. It has a _____ membrane with ____ which allow mRNA to enter the cytoplasm.

Chromosomes associated with histone proteins are located in the nucleus. It has a double membrane with pores which allow mRNA to enter the cytoplasm.

_____ are composed of DNA wrapped around histone proteins.

Chromosomes are composed of DNA wrapped around histone proteins. The DNA is the genetic information with information for growth and development of the cell.

The ______ is responsible for aerobic respiration and producing ____.

The mitochondrion is responsible for aerobic respiration and producing ATP.

Plants have large _____ involved in storing nutrients. Small ones are found in animal cells and are involved in the removal of waste.

Plants have large vacuoles involved in storing nutrients. Small ones are found in animal cells and are involved in the removal of waste.

______ are specialised vesicles, which contain enzymes. They are involved in digestion of large molecules.

Lysosomes are specialised vesicles, which contain enzymes. They are involved in digestion of large molecules.

The ______ endoplasmic reticulum is a membrane structure with ribosomes attached. It is the site of _____ synthesis, and is involved in transporting proteins to the _____ Apparatus.

The rough endoplasmic reticulum is a membrane structure with ribosomes attached. It is the site of protein synthesis, and is involved in transporting proteins to the Golgi Apparatus.

The _____ endoplasmic reticulum is a membrane structure without ribosomes attached. It is involved in _____ synthesis, and detoxification.

The smooth endoplasmic reticulum is a membrane structure without ribosomes attached. It is involved in lipid synthesis, and detoxification.

The _____ _______ modifies and packages proteins to be exported from the cell.

The Golgi apparatus modifies and packages proteins to be exported from the cell.

The _____ is composed of protein microtubules, and is involved in maintaining cell shape, moving organelles, and nuclear division (mitosis and meiosis).

The cytoskeleton is composed of protein microtubules, and is involved in maintaining cell shape, moving organelles, and nuclear division (mitosis and meiosis).

True or false: all organisms, including unicellular organisms, carry out the following processes of life: homeostasis, excretion, metabolism, growth, nutrition, response to stimuli, movement, reproduction

True: all organisms, including unicellular organisms, carry out the following processes of life: homeostasis, excretion, metabolism, growth, nutrition, response to stimuli, movement, reproduction

_____ is the removal of metabolic waste.

Excretion is the removal of metabolic waste.

Fungal hyphae that are not separated by septa, forming one long multinucleate cell are called _____ _____ _____

Fungal hyphae that are not separated by septa, forming one long multinucleate cell are called aseptate fungal hyphae

____ _____ cells, also known as muscle fibers, are multinucleate.

skeletal muscle cells, also known as muscle fibers, are multinucleate.

Red blood cells, also known as erythrocytes, do not have a _____.

Red blood cells, also known as erythrocytes, do not have a nucleus.

Phloem sieve tube elements do not have a _____.

Phloem sieve tube elements do not have a nucleus.

Practice identifying structures based on electron micrographs using the slides.

Where are ribosomes found?

floating in the cytoplasm of prokaryotic and eukaryotic cells, as well as attached to the rough ER in eukaryotic cells

Draw the nucleus

refer to the slides

Draw the mitochondria

refer to slides

Draw a sap vacuole

refer to slides

Draw the rough ER

refer to slides

Draw the smooth ER

refer to slides

Draw the Golgi Apparatus

refer to slides

Draw the chloroplast

refer to slides

Draw a chromosome

refer to slides

Draw an animal cell plasma membrane

refer to slides

Draw a plant cell plasma membrane

refer to slides

Draw secretory vesicles

refer to slides

Draw microvilli

refer to slides

The ______ theory proposes that a large cell engulfed a small aerobic prokaryotic cell. The small cell was not digested, but developed a ______ relationship with the host cell.The aerobic cell evolved into _____.

The Endosymbiotic theory proposes that a large cell engulfed a small aerobic prokaryotic cell. The small cell was not digested, but developed a mutualistic relationship with the host cell.The aerobic cell evolved into mitochondria.

In the endosymbiotic theory, the photosynthetic prokaryote evolved into _____.

In the endosymbiotic theory, the photosynthetic prokaryote evolved into chloroplasts.

Supporting endosymbiotic theory, chloroplasts and mitochondria share many characteristics with modern prokaryotes, including...

- a single ____ chromosome with naked DNA

- _____ for synthesizing proteins

- Reproducing in the same manner through a process called ____ _____

Supporting endosymbiotic theory, chloroplasts and mitochondria share many characteristics with modern prokaryotes, including...

- a single circular chromosome with naked DNA

- ribosomes for synthesizing proteins

- Reproducing in the same manner through a process called binary fission

____ cells are undifferentiated cells that are capable of differentiating into specialized cells and endlessly reproducing.

Stem cells are undifferentiated cells that are capable of differentiating into specialized cells and endlessly reproducing.

_____ tissue in plants contains cells that are:- undifferentiated cells- capable of differentiating into specialized cells- capable of endlessly reproducing

meristematic tissue in plants contains cells that are:

- undifferentiated cells

- capable of differentiating into specialized cells

- capable of endlessly reproducing

Why evolve multicellularity?

higher efficiency, longer life spans, better protection, able to consume smaller organisms

Evidence suggests Earth's prebiotic atmosphere was primarily composed of _____, ________, and _______ with smaller amounts of ________ and _________.

Evidence suggests Earth's prebiotic atmosphere was primarily composed of nitrogen, carbon dioxide, and water vapor with smaller amounts of methane and hydrogen.

______ compounds are carbon-containing molecules excluding oxides and carbonates

Organic compounds are carbon-containing molecules excluding oxides and carbonates

_______ compounds are all the other compounds that are not organic

Inorganic compounds are all the other compounds that are not organic

There was no oxygen gas or ozone present in prebiotic Earth's atmosphere because oxygen gas was first released into the atmosphere by ________

There was no oxygen gas or ozone present in prebiotic Earth's atmosphere because oxygen gas was first released into the atmosphere by photosynthesis.

In prebiotic Earth, the lack of an ______ _______ resulted in high levels of ultraviolet light entering the atmosphere.

In prebiotic Earth, the lack of an ozone layer resulted in high levels of ultraviolet light entering the atmosphere.

The high concentrations of carbon dioxide resulted in higher temperatures due to the _______ effect.

The high concentrations of carbon dioxide resulted in higher temperatures due to the greenhouse effect.

Oparin and Haldane proposed that _____ generation of organic compounds occurred on early Earth due to energy from uv light, higher temperatures, lightning and volcanic activity.

Oparin and Haldane proposed that spontaneous generation of organic compounds occurred on early Earth due to energy from uv light, higher temperatures, lightning and volcanic activity.

Cell theory states that:

1.

2.

3.

Cell theory states that:

1. Cells are the basic unit of life

2. All organisms are composed of at least one cell

3. All cells come from pre-existing cells

The following were required for the development of the first cells:

-

-

-

-

The following were required for the development of the first cells:

- Catalysis

- Self-replication of molecules

- Self-assembly

- The emergence of compartmentalism

Miller Urey attempted to stimulate the conditions of _________ in a laboratory setting

Miller Urey attempted to stimulate the conditions of prebiotic Earth in a laboratory setting

Draw the miller urey experiment. Label all components.