Biology Chapter 4 study guide
What are similarities and differences between prokaryotic and eukaryotic cells?
SIMILARITIES -Both contain DNA (genetic material) arranged in chromosomes -Both have ribosomes and organelles that use information from the chromosomes to make proteins. -Both have cytoplasm, the material inside the cell (except the nucleus). This consists of cytosol, a semifluid substance within the cell and everything else other than the nucleus. - Both have semipermeable plasma membrane DIFFERENCES: -Prokaryotes lack membrane-enclosed compartments called organelles and they do not have nuclei
What is a ribosome? What is its function in a cell? Where do find them in a cell?
Site of protein synthesis: translation of RNA into polypeptide Ribosomes are made of ribosomal RNA and a protein complex. Ribosomes are NOT membrane-bound organelles- in eukaryotes they are free in cytoplasm, attached to endoplasmic reticulum or inside mitochondria and chloroplasts. In prokaryotic cells ribosomes float freely in the cytoplasm.
What is a plasmodesmata? What's their function? Where do you find them?
A type of cell junction found in plants only. Made of fused vacuoles that allow cytoplasm to flow from one cell to another. Facilitate communication between plant cells and make the plant one continuous system.
How are microfilaments and microtubules alike?
-Both give the cell shape and support. -Both made of proteins -Movement of cytoplasm -Movement of organelles and chromosomes
What is the function of Lysosome?
-Contain hydrolases (digestive enzymes), site where macromolecules are hydrolyzed into monomers -Break down large molecules and thus act as the site of intracellular digestion
What structure do you find in prokaryotic cell?
-Prokaryotic cells do NOT have a nucleus -Are enclosed by a plasma membrane -Have DNA located in the nucleoid -The rest of Cytoplasm consists of: -Cytosol (water and dissolved material) and suspended particles -Ribosomes - sites of protein synthesis
What is the function of the Golgi apparatus?
-Receives proteins from the RER- can further modify them -Concentrates, packages, and sorts proteins -Adds some carbohydrates to proteins -The site of polysaccharide synthesis in plant cells
What kinds of cytoskeleton structure do you find in a cell?
-microtubules -microfilaments -intermediate filaments
What are four essential components for a cell?
1. Cell membrane: -selectively permeable barrier -important in communication and receiving signals 2. Cytoplasm - cytosol (water and soluble particles) 3. DNA - a genetic material 4. Ribosome - the place for protein synthesis
Why do mitochondria and chloroplast have their own DNA and ribosomes?
According to the theory of endosymbiosis, an early eukaryotic cell engulfed but did not digest a prokaryotic cell. The prokaryotic cell lived in a symbiotic relationship within the host cell and became a specialist in energy production.
What are desmosomes? What's their function? Where do you find them?
Desmosomes affix cells together in strong sheets, but they allow some materials to move in the extracellular matrix. Found in animal cells (ex skin)
What are gap junctions? What's their function? Where do you find them?
Gap junctions channels that run between membrane pores in adjacent cells, allowing substances to pass between cells (similar to plant plasmodesmata) Found in animal cells (ex cardiac muscle electric current)
What are glyoxysome and peroxisome?
Glyoxysomes: found only in plants, where lipids are converted to carbohydrates for growth Peroxisomes: collect and break down toxic by products of metablosm such as hydrogen peroxide using special enzymes
What is an endomembrane system?
Makes up many diff structures: endoplasmic reticulum, golgi apparatus, nuclear envelope, lysosomes, plasma membrane - Performs metabolic functions - regulates protein traffic within the cell
What are organelles?
Membrane enclosed compartments
How do microfilaments and microtubules differ?
Microfilaments: -solid rods made of a protein called actin -smallest fibers of cytoskeleton -Dynamic instability allows quick assembly or breakdown of cytoskeleton -fix organelles in place and bear tension, assist cell mobility Microtubules: -thick hollow rods with walls made of subunits called tubulin, a globular protein -Give pressure resistance -Separate chromosomes during cell division -The thickest of the fibers that make up the cytoskeleton
What is a nucleus and a nucleolus?
Nucleus- the "brain center" of the cell, contains the chromosomes, which contain most of the cells DNA. DNA replication and transcription occur within the nucleus. Nucleolus- dense region within the nucleus where ribosomal RNA is made.
What is a vacuole?
Occur in some eukaryotes (mainly plants and fungi) serve several functions: -storage of waste products and toxins -structure for plant cells -reproduction -catabolism-breakdown of waste -osmotic balance-control water in and out
What are the differences between RER and SER?
RER: -Has ribosomes attached to begin protein synthesis -New proteins enter the RER lumen -Proteins are chemically modified and tagged for delivery -RER participates in transport of proteins to other organelles -All secreted proteins and most membrane proteins pass through the RER SER: -More tubular, no ribosomes -Chemically modifies small molecules such as drugs and pesticides (detoxification) -Site of synthesis of lipids and steroids (hormones) -Site of glycogen degradation in animal cells -Stores calcium ions req for muscle contraction
What are tight junctions? What's their function? Where do you find them?
Tight junctions seal off adjoining cells, preventing extracellular fluids from moving across a cell layer. Hold neighboring cells together tightly and prevent dissolved molecules from moving between the membranes. Found in animal cells (ex stomach lining)
What is the main difference between intermediate filaments and other cytoskeleton?
Unlike the rest of the cytoskeleton, intermediate filaments are relatively fixed in place and do not disassemble.