Cell Structure- Unit 2 Flashcards
Intestinal bacteria and example
Helpful intestinal bacteria make vitamins that mammals cannot. These bacterium crowd out the dangerous germs. E. coli is one of the most common intestinal bacteria, only a few out of the hundreds of strains are harmful, serious if even as few as 10 are ingested.
Bacteria is synonymous with
Germs
Cell
Smallest unit that has the properties of life
Common traits in all cells (3)
Each has
A plasma membrane- a cells outermost membrane. A lipid bilayer provides is the structural foundation of cell membranes and organelle membranes. In animal cells it’s like a fluid peel (skin of a grape)
Cytoplasm- Semifluid substance enclosed by a cells plasma membrane “holds organelle like smoothie holds straw”. As we dehydrate cytoplasm will harden
Nucleus- Organelle with 2 membranes that holds a eukaryotic cell’s DNA.
Antibodies
Used to treat bacterial infections (NOT VIRUSES), we are fatigued after taking them because it kills the good stuff too. Like a grenade, all things in range are subject
Bacterial Cell and what they are similar to
Bacteria are single-celled organisms, without nucleus. Archaean are similar in overall structure.
Constraints on Cell Size
Surface-to-volume ratio limits cell size. If cells is too big the inward flow of nutrients and outward flow of wastes across the membrane can’t occur fast enough for a cell to survive.
Ratio is found by when objects volume increases with a cube of diameter, but surface area increases with square of diameter
Cell Theory (4 parts)
- All living organisms consist of one or more cells
- A cell is the smallest unit of life individually alive
3.All living cells come from division of preexisting cells - Cells contain hereditary material which they pass to offspring in division
How do we see cells
Various types of microscopes and various techniques to reveal cells and their details. Cells are so small the relevant measurements would be absurd for every day use
Membrane structure and function
A membrane functions as a selectively permeable barrier that separates an internal environment from an external. Lets in nutrients, proteins, and water (proteins is #1) Membranes can mostly be described as a fluid mosaic of lipids (phospholipids) and proteins. Organized as a lipid bilayer
Fluid Mosaic
2D model of a cell where membrane is bendable with molecules moving. Contains many different molecules inside
Basic Cell
At it’s most basic, cell is a lipid bilayer bubble filled with fluid.
Membrane proteins and what do they have
Proteins associated with a membrane carry out most functions.
All membranes have transport proteins.
Plasma membranes also have receptor, adhesion, enzymes, and recognition proteins
Types of proteins
Transport protein- passively or actively assist specific ions across a membrane
Adhesion- helps cells stick together in tissues
Receptor- binds to a particular substance outside of the cell. Tags bad cells and tells your body to kill it.
Recognition- tags a cell as belonging to self
Cell Wall Variations
Archaeans do not build phospholipids with fatty acids, instead the phospholipid tails form covalent bonds with one another. Archaean membranes are far more rigid than those of bacteria or eukaryotes.
Most Archaean consist of proteins
Most bacterial consist of peptide (chained amino acids) and polysaccharide polymers.
Sticky polysaccharides form a slime layer, or capsule, around the cell wall of many bacteria
Single-celled bacteria and Archaeans
The smallest and most diverse forms of life.
The cytoplasm contains ribosomes and plasmids.
A single, circular chromosome is located in the nucleoid
Many have cell wall, flagella, or pili
Possess few internal membrane-enclosed compartments
Smallest and structurally simplest cells
Most numerous
Ribosome
Protein synthesizing organelle (makes proteins)
Nucleoid
Region of cytoplasm where DNA is concentrated inside a bacterium or archaean. (oid-similarity)
Flagellum
Long, slender, cellular structure used for motility (mobility in cells using energy) works like a tail
Pilus
A long thread of protein subunits (protein filament) that projects form bacterial cells surface allowing for clinging, motion or plasmid transmission (carry DNA genes)
Cell Wall
Semi-rigid but permeable structure that surrounds the plasma membrane of some cells
Uniqueness of Eukaryotic Cells
Start out life with membrane-enclosed organelles including nucleus
Contain endomembrane system (ER, vesicles, and Golgi bodies), mitochondria, and cytoskeleton
Nucleus
Contains cell’s genetic material (DNA)
Has a double-membraned nuclear envelope that surrounds cytoplasm
Nuclear Envelope
Controls passage of certain molecules between nucleus and cytoplasm
Receptors and transporters stud from both sides, other proteins for nuclear pores
Double membrane’s outer bilayer is continuous with ER membrane
Endomembrane System
Includes rough and smooth endoplasmic reticulum (ER), vesicles, and Golgi
Makes and modifies lipids and proteins and recycles and disposes of molecules and particles
Endoplasmic Reticulum (ER)
An organelle extension of the nuclear envelope consisting of a continuous system of sacs and tubes.
Site where new polypeptide chains are modified
Vesicles
Small membrane-enclosed saclike vesicles form in a variety of types, either on own or by budding
Transport substances from one organelle to another, store, or degrade.
Lysosome, peroxisome and vacuole
Lysosome
Enzyme-filled vesicle that functions in intercellular digestion
Peroxisome
Enzyme-filled vesicle that breaks down amino acids, fatty acids, and toxins
Vacuoule
A fluid filled organelle that isolates or disposes of waste, debris, or toxic materials
Central vacuole is fluid-filled vesicle in many plant cells
Golgi Body
Enzymes in a Golgi body finish protein and lipids that are delivered by vesicles from the ER.
Modifies polypeptides and lipids, attaches phosphate groups and cuts polypeptides
Sorts and packages the finished products into vesicles that carry them to lysosomes or to the plasma membrane
Mitochondria
make ATP by breaking down compounds in the oxygen-requiring pathway of aerobic respiration
Double membraned organelle
During aerobic respiration hydrogen ions accumulate between 2 membranes, the build up causes the ions to flow across the inner mitochondrial membrane through membrane transport proteins that drive formation of ATP
No mitochondria- no ATP- no energy
Chloroplasts
Plastids that produce sugars by photosynthesis. Stacks of green coins, could be plant, protist, or bacteria.
Theory of Endosymbiosis
Mitochondria evolved from aerobic bacteria that took up permanent residence inside a host cell.
Reasons: Resemble bacteria in size, form, and biochemistry
Have their own DNA, similar to bacterial DNA
(This means body contains more than one type of DNA, digestive tract isn’t even own body
Divide independently of the cell (have own ribosomes)
Plastid
Organelle that functions in photosynthesis or storage (chloroplast or amyloplast)
Dynamic Cytoskeleton
Cells aren’t shapeless blobs, like multicellular organisms they rely on a skeleton (without bones). Consists of microtubules, microfilaments, and intermediate filaments. Dynamic (moves around) framwork of protein filaments that support, organize, and move cells and their internal structures (tissues need movement to grow)
Accessory Molecules
Cells move in ways analogous to the way that we skeleton-using vertebrates do. Relying on cytoskeletal elements
Motor proteins
Motor Proteins
Energy-using proteins that interact with cytoskeletal elements to move the cells parts or whole cell when energized by phosphate-group transfer from ATP
Pseudopods
Also known as false feet.
Move the cell and engulf their prey. Motor proteins attached to microfilaments drag the plasma membrane
Extracellular Matrix (ECM)
Complex mixture of cell secretions (fibrous stringy proteins and polysaccharides) that surround cells
Supports cells and tissues
Has roles in cell signaling
Cuticle
Type of ECM
Secreted covering at a body surface
Chitin covering protects arthropods
Waxy coat protects plant’s exposed surfaces. keeps moisture inside
Fresh water fish are one of only organisms that don’t need a cuticle
Animal ECM
Consists of various carbohydrates and proteins. Basis of tissue organization and provide structural support
Bone is mostly extracellular matrix composed of collagen (fibrous protein hardened by mineral deposits)
Living bone isn’t brittle, usually flexible unless weight bearing
Plant ECM
Plant cell wall is a type of ECM. Pliable primary walls enclose secondary walls strengthened with ligin
Cells walls are in
Plants, bacteria, fungi, and algae
Parallel structures
Different types of eukaryotes have different structures that contain of different things but do the same job (different burger joints)
Cell junctions
In animal tissues, cells are connected to their neighbors and to ECM by cell junctions
Cells send and receive ions and signals through junctions
Others help cells recognize and stick to each other and to ECM
Difference between plant cells and animal cells
Plants- central vacuum, cytoplasm, cell wall
Animals- don’t have cells walls, or cnetral vacuum
Life
Property that emerges from cellular components but a collection of these components in the same amounts and proportions is not necessarily alive (dead bodies are dead no matter if cells are organized right)
Characteristics of living things (6)
They make and use organic molecules of life
They consist of one or more cells
They engage in self-sustaining biological processes (metabolism and homeostatis)
They change over their time by growing, maturing, and aging
They use DNA as hereditary material
They have the collective capacity to change over successive generations by adapting to environmental pressures
