BSC2010 Exam 1: Cells

cell theory

Cells are the fundamental units of life

all organisms are composed of cells

all cells come from preexisting cells

prokaryotic cell

without membrane enclosed compartments

Eukaryote

A cell that contains a nucleus and membrane bound organelles

Similarities of Prokaryotes and Eukaryotes

DNA

ribosomes

cytosol

cell membrane

nuclear envelope

eukarytoic

layer of two membranes that surrounds the nucleus of a cell

Differences between plant and animal cells (eukaryotic)

plants have rigid cell walls

plants have central vacuoles

plants have plastids (chloroplast)

plants have plasmodesmata (cell junctions)

Ribosomes

site of protein synthesis

is not membrane-bound

has its own DNA

Nucleus

site of DNA and RNA repication

DNA transcription to RNA

it contains nucleolus (where ribosomes begin to be assembles from RNA and proteins)

DNA combines with proteins to form chromatin in long, thin threads called chromosomes

endomembrane system

The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.

endomembrane system includes

nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles and the plasma membrane.

Rough Endoplasmic Reticulum

has ribosomes, makes proteins

Smooth Endoplasmic Reticulum

no ribosomes

site of glycogen degradation in animal cells

site of synthesis of lipids and steroids

stores calcium ions required for muscle contration

Lysosomes

cell organelle filled with enzymes needed to break down certain materials in the cell

when phagosomes combine with primary lysosomes they form secondary lysosomes

Golgi apparatus

is composed of flattened sacs (cisternae) and small membrane-enclosed vesicles

receives proteins from the RER and further modifies them

concentrates, packages, and sorts proteins

Adds carbs or sugars to proteins

site of polysaccharide synthesis in plant cells

energy transforming organelles

molecules first broken down in the cytosol

the partially digested molecules enter the mitochondria Make ATP

Mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production

Plastids

A group of membrane‐bound organelles commonly found in photosynthetic organisms and mainly responsible for the synthesis and storage of food.

Chloroplasts

components of chloroplasts

thylakoids stack together to form granum

Carbohydrates synthesis occurs in the stroma(fluid surrounding the thylakoids)

vacuoles

occur in some eukaryotes but mainly in plants and fungi

storage

structure for plant cells (turgor pressure)

reproduction

catabolism

smooth ER

detoxifies toxins

Rough ER

produces secretory proteins

photosynthetic plant cells have

chloroplasts

skeletal muscles require a lot of energy

so they have a lot of mitochondria

Cytoskeleton

supported and maintains cell shape

holds organelles in position

moves organelles

is involved in cytoplasmic streaming

interacts with extracellular structures to anchor the cell in place

three components of the cytoskeleton

microfilaments, intermediate filaments, microtubules

Microtubules

largest diameter

form rigid internal skeleton for cells

act as framework for motor proteins to move structures in the cell

microfilaments

help a cell or parts of a cell to move

determines cell shape

microfilaments are polymers made of two intertwined strands of the protein (ACTIN)

dynamic and often change organization and length in a cell

intermediate filaments

very diverse

have tough ropelike protein assemblages

anchor cell structures in place (nucleus)

resist tension

maintain rigidity-resits tension and pressure from outside forces

extracellular structures

are composed on molecules secreted to the outside of the plasma membrane

extracellular structures in eukaryotes

prominent fibrous macromolecule

gel-like medium with fibers embedded

plant cell wall

semi-rigid structure outside the plasma membrane

fibrous(polysaccharide cellulose)

gel-like matrix(cross-linked polysaccharies and proteins)

plant cell wall major roles

provides support

barrier to infection

contributes to form during growth and development

Animal cell extracellular matrix

fibrous(collagen)

gel-like matrix(proteoglycans)

role od extracellualr matrix in animal cell

holds cells togeher

physical properties

filter materials

orient cell movement during growth and repair

cell junctions

are specialized structures that glue adjacent cells together

tight junctions

quilted seal

intestines

prevent substances from moving through space between cells

desmosomes

anchoring junctions

skin

hold cells together but allow materials to move in the matrix

gap junctions

heart with ions/electrical current

channels that run between membrane pores in adjacent cells (plasmodesmata)