Eukaryotes

Nuclear Envelope

two phospholipid bilayers membranes

What are Nuclear Pores?

filled by proteins and act as molecular channels, permitting certain molecules from passing into or out of the nucleus

Proteins

act as enzymes that enter the nucleus to help in nuclear activities like transcription or become incorporated in nuclear structure

RNA

mRNA that is synthesized and sent out to cytoplasm

What are Nuclear Lamins ?

the inner surface of the nucleus is covered by intermediate filament fibers that keep shape

What happens with ribosomes in the Nucleolus?

rRNA is synthesized from DNA in the nucleolus. rRNA is assembled with proteins, forming ribosomal subunits that pass through the nuclear pores to the cytoplasm where they combine to form ribosomes

What is chromatin?

DNA that is spread in the nucleus. condensed to chromosomes during cell division

What is the Structure of Chromosome?

each chromosome is made of nucleosomes. nucleosomes are made of a core histone with DNA that coils around it. the core histone is made of 8 histones (2 H2A, 2 H2B, 2 H3, 2H4). they are connected by linker DNA and a spacer histone (H1)

What proteins do Free Ribosomes make?

NMPO PC

nuclear proteins, mitochondrial proteins, proteins found in other organelles, proteins found in cytoplasm

What do ER Ribosomes make?

M PE PX

membrane proteins, proteins found in endomembrane systems like lysosome enzymes, proteins exported from the cell

What is the Endomembrane System?

group of membranous structures in eukaryotes that interact through direct communication or by transfer of membranous vesicles

What is in endomembrane system?

Nuclear envelope

Golgi apparatus
Various vacuoles
plasma membrane
ER
lysosomes

What is the Endoplasmic Reticulum?

system of channels forming connected canals that carry proteins and other substances through the cytoplasm from one area to another

What is Rough ER?

studed with ribosomes where proteins are synthesized and exported to certain areas

What are Signal Sequences ?

special amino acid sequences that direct proteins to their destinations

Smooth ER

no ribosomes but enzymes embedded in membrane

What does smooth ER do?

1. catalyze synthesis of lipids like steroid hormones

2. . catalyze carbohydrate metabolism synthesis

3. detoxify drugs in liver like morphine by chemically modifying them

4. help in muscle contractions by regulating calcium ions in muscles

How does smooth ER regulate calcium?

it stores intercellular calcium, keeping cytoplasmic calcium level low, allowing calcium to be used as a signal molecule

Where do proteins and lipids synthesized in RER and SER go?

lipids and proteins synthesized in RER and SER will be transported to golgi apparatus by vesicles

What is the Golgi Apparatus ?

flattened stacks of membrane with a front and back. front is called cis face (receiving end) and the back is the trans face (discharging end)

What is the Function of Golgi Apparatus?

receive protein and lipid filled vesicles that bud from ER

What does golgi apparatus do?

contains enzymes that modify proteins and lipids. enzymes add sugar to proteins making glycoproteins and add sugar to lipids making glycolipids. vesicles leave the Golgi apparatus to different areas where they discharge their contents

What are lysosomes ?

membrane bound vesicles. their hydrolytic enzymes and lysosomal membrane proteins are made by RER and transferred to golgi apparatus for processing

Function 1 of Lysosomes

intracellular digestion through phagocytosis. the food vacuole fuses with lysosomes whose enzymes digest the food, the digested products like simple sugars, amino acids, and other monomers pass to the cytosol and become nutrients

Function 2 of Lysosomes

lysosomes engulf another organelle and break down old organelles through autophagy

Function 3 of Lysosomes

programmed destruction of cells by their own lysosomal enzymes

Examples of Metamorphosis

transforming of tadpole into frog, lysosomes in the cells of the tail destroy those cells

the hands of human embryos are webbed until lysosomes digest the tissue between the fingers

What happens with phagocytosis and white blood cells?

white blood cells will take in bacteria by phagocytosis where lysosomes fuse with the resulting food vesicle, releasing their enzymes and degrading bacterial cells

What are Primary Lysosomes ?

lysosomes that are not functioning actively and do not maintain acidic internal pH

What are Secondary lysosomes?

when primary lysosomes fuse with food vesicles or organelles, it activates proton pump in the lysosomes. then the pH falls which activates lysosomal hydrolytic enzymes

What are peroxisomes ?

enzyme bearing, membrane enclosed vesicles

Function 1 of Peroxisomes

use oxygen to breakdown fatty acids into smaller molecules that can be transported to mitochondria as fuel

Function 2 of Peroxisomes

peroxisomes in liver detoxify alcohol by transferring hydrogen from the poison to oxygen, producing hydrogen peroxide. peroxisomes contain the enzyme catalase which breaks hydrogen peroxide down into water and oxygen

What is the Glyoxysome?

found in fat storing tissue of plant seeds. they contain enzymes that convert fatty acids to sugar which helps plants grow to the point where the plant is able to produce sugar by photosynthesis

Why are peroxisomes not considered part of the endomembrane system?

they do not bud from the endomembrane system but grow by incorporating proteins and lipids from the cytosol

Mitochondria

site for oxidative metabolism

their DNA codes for proteins essential to its oxidative metabolism

Matrix contains enzymes, DNA and ribosomes

Cellular Respiration Equation

C6H12O6 + O2 ----> H2O + CO2 +ATP

Chloroplasts (plastid)

site for photosynthesis

contains green pigment chlorophyll in thylakoid membrane

Types of Vacuoles (membrane bounded sacs)

1. food vacuoles- formed by phagocytosis

2. contractile vacuoles- found in fresh water paramecium to pump excess water out of the cell
   3. mature plants have large vacuole enclosed by tonoplast

Functions of large central vacuoles

1. store organic compounds (sugar, amino acids)
2. store inorganic ions like K+ and Cl-
3. disposal site for plants
4. some contain pigments that color the cells
5. contain poisons that protect plants against predators