BIO 120 Midterm USASK (lecture 1-5)

Biology

the study of life

Life

characteristics of living things

Organism

an assembly of molecules functioning as a more or less stable whole that exhibits life

Autotrophs

organisms retain energy (self)

Heterotrophs

rely on other organisms for energy

characteristics of life

- display order and have complex energy

- harness and utilize energy

- respond to stimuli

sexual reproduction

- two parents, the fusion of gametes

- offspring are genetically unique

- increases genetic variation

asexual reproduction

- one parent, no fusion of gametes

- offspring are all genetically identical

cell theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

reproduction

process of making the next generation

Transmission Electron Microscopy

- beams of electrons are transmitted through the sample

- thin slices stained with heavy metals

Scanning Electron Microscopy

- sample coated with a heavy metal

- beams scan surface to make 3D image

microscopy

to view objects that cannot be seen with the naked eye

Magnification

ratio between size of image produced and actual size

resolution

ability to observe two adjacent objects as distinct from one another

contrast

how different one structure looks from another --> enhanced by dyes

flourescence microscopy

- fluorescence used to generate image

- allows for in vivo studies

- specimen is illuminated with light of a specific wavelength which is absorbed except for the fluorophores

Finite life span

occasionally breaks down and can be repaired or discarded

- renewal goes on constantly throughout the life time and arise by division

cells: simple logistics

specialized cells are easier to replace without disruption of a function

cell metabolic demands

- fuel from complex nutrients

- elimination of waste products

limiting factor in cell metabolism

transport

Passive transport

diffusion/osmosis, movement the need of energy input

Active transport

sodium/potassium pump, movement on ions or molecules into region of higher concentration

cells cannot increase in size beyond certain limits because:

- speed of diffusion

- surface area/volume ratio

microvilli

increase surface area

Carl von Linne

father of modern taxonomy (modern naming system)

Taxonomy

science of defining and naming groups of biological organisms on the basis of shared characteristics

Prokaryote domains

Bacteria and Archaea

Eukaryote domains

Eukarya

Prokaryote nucleus

nucleoid region has no boundary membrane

Eukaryote nucleus

true nucleus, separated from the surrounding cytoplasm by membranes

Eukaryote Cytoplasm

contains extensive membrane systems that form organelles

all living organisms contain _____ that is made of ________

genetic material; DNA (deoxyribonucleic acid)

Shapes of prokaryotic cells

1. spherical (Cocci)

2. Rodlike (Bacilli)

3. Spiral (Spirochetes)

prokaryotic ribosomes

float freely in the cytoplasm --> assemble amino acids into proteins

plasma membrane

surrounded by external cell wall coated with glycocalyx composed of polysaccharides

Flagella

what bacteria and archaea use to move

- rotates in a socket and pushes the cell through liquid medium

bacterial hair like pili

attach the cell to surfaces or other cells

special sex pilus

joins bacteria during mating

cyanobacteria

- only prokaryotes able to produce oxygen

- only prokaryote with internal membranes (thylakoids)

origin of eukaryotic cells

union of bacteria and archaea

modern phototrophic eukaryotes acquired _____

photosynthetic capabilities from cyanobacteria by endosymbiosis

Theory of endosymbiosis

suggests that mitochondria and chloroplasts evolved from ingested prokaryotes

cyanobacteria

chloroplasts are said to be descended from

aerobic bacteria

mitochondria are said to be descended from

energy transforming organelles in all eukaryotic cells

mitochondria and chloroplasts

mitochondria have ___

their own DNA, separate from the DNA found in nucleus

mtDNA

- passed down from mom to child

- accumulates changes more slowly than other types of DNA

cytoplasm of eukaryotic cells

gel like complex mixture of cytoskeleton filments, dissolved molecules and water enclosed within the cell membrane and organelles

Subcellular fractionation

the process of separating cellular components while preserving individual functions of each component

Endomembrane system

- interrelated internal membranous sacs

- divide the cell into functional and structural compartments

- membranes are connected directly or indirectly by vesicles

vesicles

small membrane bound compartments that transfer substances between parts of the system

parts of a cell/components of endomembrane system

- outer membrane of nuclear envelope

- endoplasmic reticulum

- golgi apparatus

- lysosome

- peroxisomes

- secretory vesicles

- vacuoles

- plasma membrane

multinucleated cells

eukaryotic cell that has more than one nucleus per cell

mitosis in multinucleated cells

- occur in a coordinated manner and nuclei divide simultaneously

- occur asychronously where nuclei divide independently

nucleus of eukaryotic cells

- contains most of the cells genetic material

- genes are organized into chromosomes

chromosomes

multiple long linear DNA molecules complex with proteins

histones

very basic protein with high pH

nuclear envelope

- one of the main structures making up the nucleus

- network of protein filaments reinforces the nuclear envelope in animal cells

- contains nuclear pores

anucleated cells

red blood cells

nuclear pores

- large, octagonally symmetrical and cylindrical structure

- formed of many types of proteins called the nuceloporins

- cross both nuclear membranes

- regulate transport of molecules across the envelope

nuclear envelope is ___ to ____ molecules

impermeable; large

nucleoplasm

the liquid or semi liquid substance within the nucleus

- most of the space inside the nucleus is filled with chromatin

the nucleoli

- nuclear structure formed around the genes coding for ribsomic RNA (rRNA)

- site of ribosomal subunits synthesis

ribosomal subunit synthesis

- rRNA exit the nucleus through nuclear pore complexes

- form ribosomes in the cyotplasm

nuclear localization signal

proteins move from the cytosol into the interior of the nucleus --> targeted to the nucleus by the _____ sequence

cells synthesize

proteins, lipids, carbohydrates, nucleic acids

ribosomes

- composed of: one or more rRNA and a variety of proteins

- the site of translation of mRNA into a polypeptide chain

- consist of two major subunits

- primary enzymatic function is to form peptide bonds

peptidyl transferase

aminoacyltransferase that forms peptide bonds between adjacent amino acids carried by tRNA

two subunits of ribosomes

- small subunit reads the mRNA

- catalytic subunit

ribosome location

- some are freely suspended in to cytosol

- others are attached to membranes (nuclear membrane or rough ER)

proteins made on free ribosomes in the cytosol may

1. remain in the cytosol

2. pass through the nuclear pores into the nucleus

3. become parts of mitochondria, chloroplasts, the cytoskeleton, or other cytoplasmic structures

proteins that enter the nucleus become

1. part of chromatin

2. line the nucleus envelope such as the lamins

3. remain in solution in the nucleoplasm

endoplasmic reticulum

- interconnected network of membranous channels and cisternae

- two forms

two forms of the ER

1. rough ER (has ribosomes attached to the surface)

2. smooth ER

structure of the ER

- surrounded by phospholipid membrane

- lumen filled with the secretory products of the cell

- membrane encloses the cisternal space

functions of the ER

1. forms skeletal framework

2. active transport of cellular materials

3. metabolic activities due to presence of different enzymes

4. provides increased surface area for cellular reactions

5. formation of nuclear membrane during cell division

Rough ER

- ribosomes on outer surface

- proteins made on ribosomes enter the ER lumen where they fold into their final form

- involved in the chemical modifications of proteins

- proteins are then delivered to other regions of the cell

smooth ER

- connected to the nuclear envelope

- no ribosomes attached to their surface

protein synthesis and rough ER

- integral membrane proteins are inserted into the rough ER membrane as they are synthesized

- signal peptide is then cleaved off within the lumen of the ER

functions of the smooth ER

- synthesizes lipids that become part of the cell membrane

- regulation of osmosis

- regulation of intracellular calcium concentration

- carbohydrate metabolism

transfer of lipids to other membranes

- lipids in the ER membrane can diffuse laterally to nuclear envelope

- lipids can be transported via vesicles to Golgi, lysosomes, vacuoles or plasma membrane

- lipid exchange proteins

carbohydrate metabolism

- glycogenolysis occur in the smooth ER

- smooth ER contains glucose-6-phosphate which is converted to glucose and Pi

detoxification in the smooth ER

- increased activity of detoxification enzymes

- hypertrophy of the smooth ER

golgi complex

- differentiated portion of the ER

- composed of a stack of membrane bounded cisternae located between the ER and the cell surface

- stack has functional regions that contain different enzymes

- vesicles transport proteins between stacks

- proteins made in the ER enter on the cis face of the complex

cisternae

stack of flattened membranous sacs

protein modifications in the Golgi complex

- processing is the main function

- proteolytic enzymes cut proteins into smaller polypeptides

- proteins are chemically modified by adding functional groups such as lipids or carbohydrates

- modified proteins exit from the trans face in vesicles

sorting in the golgi complex

1. stay in the golgi

2. transported via vesicles to the ER

3. to the plasma membrane

4. to the exterior of the cell by exocytosis

Exocytosis

secretory vesicles release proteins or other contents to the exterior of the cell and then fuse with the plasma membrane

endocytosis

vesicles that bring in molecules from the exterior

- the plasma membrane bulges inward and pinches off into the cytoplasm as an endocytic vesicle which then carries the materials to the golgi or other destinations

lysosomes

- small membrane bound vesicles containing hydrolytic enzymes that digest complex molecules

- found in animals but not plants

- synthesized in the rough ER and formed by budding from the golgi complex

lysosomes parts/functions

- contain more than 50 different enzymes

- digest food molecules, worn out organelles and materials engulfed by phagocytes

- pH is acidic (5) --> ?lowered by ATP/H pump?

central vacuoles

- large vesicles that perform specialized functions unique to plants

- surrounded by the tonoplast

functions of central vacuole

store salts, organic acids, sugars, storage proteins, pigments (give flowers their colour) and in some cells waste products

cell walls

- support individual cells

- consist of cellulose fibers

pectin

- structural heteropolysaccharide contained in the primary cell walls of terrestrial plants

- produced commercially as a white to light brown powder mainly extracted from citrus fruits and is used in food as a gelling agent

- used in dessert fillings, medicines, sweets, stabilizer in fruit juices and milk drinks, source of dietary fiber

nuclear localization signal is made of

made up of proteins and amino acids