BIOL 1115 Ch. 8-13

Explain what electromagnetic spectrum is and what determines the amount of energy contain within the photon

Visible light consists of wavelength of light that produce that colours we see

different pigments are better at absorbing different wavelength of light

wavelength that are not absorbed are reflected/transmitted EG. chlorophyll appears green because it absorbs visible wavelengths other than green

Interpret an absorption spectrum and explain what it indicates regarding the colours that we see in photosynthetic tissues

An absorption spectrum plots light absorption by wavelength

- chlorophyll absorption spectrum indicates its best at absorption violet-blue and red light so these wavelength work best for photosynthesis

Name at least 3 distinct types of photosynthetic pigments and recall the colours of light they can absorb

chlorophyll

carotenoids absorbs blue and green and transmits yellow, orange or yellow light

phycobilins

Describe two reasons why it might be beneficial for autotrophs to have more than one type of pigment

Having more than one kind of pigment allows photosynthetic cells to absorb a wide range of light, increasing photosynthetic efficiency and preventing photo damage

other pigments that are also found in plants/algae are. Grouped together as "accessory pigments"

Name the two major stages of photosynthesis and state where they occur in a eukaryotic cell and the products that result from each

1. Light capturing reactions in the thylakoids membrane:

- water is split to obtain electrons, which are used to reduce NADP+ to NADPH

- ATP is formed from ADP

- O2 is released as a by product

- thylakoids transform light energy to chemical energy stored in ATP and NADH

2. Calvin cycle in the stroma

- sugars are formed using the carbon from CO2, the energy from ATP and electrons NADH

Describe the structure and function of a photo system

A photosystem is comprised of reaction centre complex surrounded by antenna chlorophyll and accessory pigments

- antenna chlorophylls funnel energy from electrons to reaction centre

- primary electron acceptor accepts high energy electrons from a chlorophyll in a reaction centre

Photosystem II: functions first and is best absorbing a wavelength of 680nm

Photosystem I: Functions second and is best absorbing a wavelength of 700 nm

Trace the movement of electrons i linear electron flow

1. Photon hits an antenna pigments and energy is transferred among pigments until it excites an electron in P680 which is in turn transferred to PEA pheophytin

2. H2O is split by enzymes and electrons are transferred to P680+ and reduce it back to P680

3. Electrons are transferred from pheophytin to a hydrophobic molecule called plastoquinone which binds to protons from stroma

4. Plastoquinone molecules carry electrons and protons through the thylakoids membrane to a short ETC that involves a protein complex called cytochrome complex

5. In PSI energy from photons is transferred from antenna pigments P700, where it excites electrons that are then transferred to primary electron acceptor, ferredoxin

6. P700+ I'd reduced again by accepting electrons from ETC via plastocyanin

7. Electrons from Ferredoxin fall down a second short ETC where NADP+ To NADPH

Trace the movement of electrons in cyclic electron flow.

- When light levels are low, light is shared evenly between PSI and PSII

- when light levels are high, the energy that's absorbed during light capturing reactions start to outspace the Calvin cycle, which needs to oxidize NADPH to NAPDP+

- if no NADP+ is being returned from Calvin, high energy electron can cause photo damage

- to prevent photo damage, electrons are shunted into alternate pathway of cyclic electron flow, which increases production of ATP but decreases production for NADPH

Describe the similarities and differences between oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts.

Similarities:

-membrane associated ETC

- creation of proton gradient

- harvesting energy of the proton gradient by making ATP with the help of STP synthase

Differences:

- oxidative involves the reduction of O2 and H2O with electrons donated by NADH and FADH2 and occurs equally well in light and dark

- phosphorylation involves oxidation of H20 to 02 WITH NADP+ as electron acceptor and is dependent on light

Describe how sugar is formed in the Calvin cycle as well we the role of ATP and NADPH in the Calvin cycle

the Calvin cycle uses ATP and NADPH to convert three molecules of CO2 to one molecule of a 3-carbon sugar. The plant can then use this small sugar to make larger sugars such as glucose and many other organic compounds.

ATP and NADPH produced by the light reactions are used in the Calvin cycle to reduce carbon dioxide to sugar. ATP is the energy source, while NADPH is the reducing agent that adds high-energy electrons to form sugar.

Ch.11

explain the utility of extra cellular layers in plants and animal cells

Most cells possess a protective layer or wall, located external to the plasma membrane

- helps define cell shape

- attaches the cell to other cells

- act as a first defence

structures as a fibre composite

- cross linked network of filament resist tensile forces

- ground substances surrounds the filament and resists compressive force

Characterize the general structure and function of a cell wall, compare and contrast primary and secondary walls with respect to both structure and function

- Most plants cells are surrounded by cell wall

- long strands of cellulose are bundled into microfibrils

- pectin surround the microfilaments to retain moisture and resist compression

Primary: plant cells lay down PCW, which define shape of cell and counteracts turf or pressure

- growing cells secrete proteins called expansins, loosen connections between microfibrils and let cells expand

secondary: converts extra strength to the cell and vary in composition

- leaf cells often have secondary that contain waxes, protecting tissues against compression

Describe the structure and function of plasmodesmata in plant cells

Plasmodesmata are much larger than gap, so they allow for similar functions and movement of RNA molecules and proteins

plasma membrane, cytoplasm and SER extend through it

Describe the structure of extra cellular matrix of animal cells and give examples of how the composition can vary

Most animal cells secrete a fibre composite called ECM

- fibrous Compton one to is mostly made from collagen

Ground substance is made from proteglycans

- proteins attached to polysaccharides

ECM allows formation of tissues in animals

- tissues are made of numerous similar cells that function as an unit

- proteins called integrin interact with element of the ECM and elements of cytoskeleton

Describe the structure and function of tight junctions, gap junctions and desmosomes in animal cells

Tight junction: forms a water tight seal between 2 cells

- prevents movement between cells, so transport can only occur in a controlled way across the plasma membrane of tissues

Desmosomes: made up of proteins that link to cytoskeleton of adjacent cells

- resist pulling and shearing forces; common in epithelial and muscle tissues

Gap: in animals, gap connects adjacent cells and form channels

- channel proteins in adjacent cells line up , allowing for:

1. Ions and small molecules to be passed back and forth

2. Regulation of gene expression in coordinated manner

3. Inactivation or activation of proteins

Ch. 12 & 13

Explain how bacteria divide

Divide by binary fission

Distinguish between replicated and unreplicated chromosome

unreplicated chromosomes consists of a single, long DNA double helix wrapped around protein

Replicated chromosome consists of two copies of the same DNA double helix

Distinguish between chromosomes, chromatin and chromatids

Chromosomes are each formed from a double helix DNA strand wrapped around his tone protein

DNA and protein material called chromatids and its usually loosely packed

After replication, each double stranded DNA copy is called chromatid

Distinguish between centrosome and centromeres

The centromere is a part of a chromosome that links the sister chromatids

Centrosome is the organelle where all the cell microtubules get organized.

List the phases of the cell cycle and describe the sequence of events that occurs during each phase.

2 distinct phases

1. M phase is the phase in which a parent cell undergoes division into 2 daughter cells; turning into haploid

2. M phase is the phase that occurs between cell division; prep for mitosis

List 5 types of proteins involved in eukaryotic cell division and describe their role

- Cohesins form rings and hold sister chromatids together

- Condensins form tings and stabilize the loops in DNA allowing the chromatin to be more compact

- Nuclear lamins are intermediate filaments that form an interface between chromosomes and inside of the nuclear envelope

- Kinetochore proteins are sites on chromosomes to which microtubules can connect

- microtubules separate chromatids and move them to opposite poles of dividing cell

Describe the spindle apparatus, including MTOCs, kinetochore microtubules, polar microtubules, and aster

microtubules

Spindle produces mechanical Forces that move replicated chromosome during early mitosis and pull chomatids apart in late mitosis

MTOCs are located at the oppposite poles of the spindle and plus end of microtubules grow outwards from the poles

- polar microtubules extend from each pole and overlap with one another in the middle

- Kinetochore microtubules are destined to attach to chromosome at their kinetochore

- Astral microtubules (animals only) anchore the MTOC to the cell membrane

Explain the role of the spindle apparatus during mitosis

They help separate the chromosomes

They attach the chromosomes and then pull to opposite poles resulting 2 identical cells with same chromosome

List the phases of mitosis and describe the events that occur in each phase

1. Interphase: chromo is composed of two sister chromatids and are replicate

2. PROPHASE: chromo condense, spindle start to form

3.PROMETAPHASE: nuclear envelope breaks down, microtubules contact chromo at kinetochore

4. METAPHASE: chromo line up in the middle of the cell

5. ANAPHASE: sis chromatids separate into daughter chromo which are pulled to opposite poles of spindle

6. TELOPHASE: nuclear envelop reforms, chromo de-condense

Compare cytokinesis in plants and animals cells

In animal cells, a ring of actin filament called contractile ring forms under the cell membrane, forming cleavage furrow that will split the cell in two

In plants, the division of the cell also requires construction of new cell

- vesicles from golgi bring plasma membrane and cell wall components to the middle of the cell, forming cell plate

Distinguish between haploid and diploid

Haploid cells have a single copy of each chromosome

diploid cells have two copies of each chromosome. 2 different alleles of each gene

Haploid (n) cells are produced from diploid cells by meiosis. 1 allele of each gene

Distinguish between sex chromosomes and autosomes

-sex chromosomes - which determine the sex of the individual

Autosomes- non sec chromosomes, Carry majority of the organism's genes

Distinguish between genes and alleles

A gene is a segment of DNA located on a chromosome that carries hereditary instructions from parent to offspring.

Allele's are the different types of genes you can be.

Distinguish between sister chromatids and non-sister chromatids

A sister chromatid is either one of the two chromatids of the same chromosome joined together by a common centromere

Non sister chromatid refers to either of the two chromatids of paired homologous chromosomes, the pairing of maternal and paternal chromosome

Describe the events that characterize each phase of meiosis

Compare and contrast mitosis, mitosis II and meiosis

Mitosis produces daughter cells that are genetically identical to the parent and to each other.

Meiosis produces cells that are genetically distinct from the parent cell and from each other.

Describe a general animal life cycle

Starts at meiosis: number of chromosomes reduced by half

fertilization: diploid number of chromosomes restored

mitosis: occurs during development; and becomes a diploid adult

Name and describe three events that contribute to genetic variation in sexually reproducing organisms

Crossing over, independent assortment,

and fertilization introducing cariation as a set of haploid of chromosomes

Define nondisjunction and explain the consequences of nondisjunction

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division

Results in half of resulting gametes missing a chromosome and other half containing an extra chromosome

Nondisjunction results in daughter cells with abnormal chromosome numbers (aneuploidy).