Prokaryotic and Eukaryotic Cells Overview

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Questions and Answers

What is the primary function of ribosomes in eukaryotic cells?

Transporting vesicles to the Golgi apparatus

Breaking down nuclear membranes

Synthesizing polypeptides from mRNA (correct)

Modifying proteins for extracellular secretion

Which structure is responsible for packaging proteins into secretory vesicles?

Golgi apparatus (correct)

Rough endoplasmic reticulum

Clathrin molecules

Nuclear membrane

What role does clathrin play in cellular function?

Regulating gene expression

Maintaining the integrity of the nuclear membrane

Forming clathrin-coated vesicles (correct)

Translating mRNA into proteins

At which point in the cell cycle does the nuclear membrane break down?

At the beginning of mitosis and meiosis Signup and view all the answers

What is the composition of the rough endoplasmic reticulum's membrane?

An extension of the nuclear membrane covered in ribosomes Signup and view all the answers

What characterizes totipotent stem cells?

They can develop into any other cell types including embryos Signup and view all the answers

What happens to proteins produced by ribosomes attached to the rough endoplasmic reticulum?

They enter the Golgi apparatus for modification and packaging Signup and view all the answers

What occurs after the vesicles from the rough endoplasmic reticulum fuse with the Golgi apparatus?

Proteins are modified and packaged into secretory vesicles Signup and view all the answers

What effect does acetylcholine have on sodium channels in the postsynaptic membrane?

It opens sodium channels. Signup and view all the answers

What is the primary role of the sodium-potassium pump in neurons?

To maintain resting potential. Signup and view all the answers

How does the sodium-potassium pump operate?

It is an active transport mechanism exchanging Na+ and K+ ions. Signup and view all the answers

What occurs after ATP attaches to the sodium-potassium pump?

The pump undergoes a conformational change after ATP is hydrolyzed. Signup and view all the answers

What is the resting potential of a neuron?

-70 mV Signup and view all the answers

What mechanism allows glucose to be transported from the small intestine into epithelial cells?

Facilitated diffusion through glucose channels. Signup and view all the answers

In what direction do sodium and potassium ions move in relation to the sodium-potassium pump?

Sodium ions move out, potassium ions move in. Signup and view all the answers

What ion is predominantly found outside the axon at resting potential?

Sodium (Na+) Signup and view all the answers

What characteristic differentiates embryonic stem cells from adult stem cells?

Embryonic stem cells are pluripotent. Signup and view all the answers

What is the primary role of morphogens during embryonic development?

They regulate gene expression based on concentration. Signup and view all the answers

Which statement is true regarding adult stem cells?

They are found in niches that support their function. Signup and view all the answers

Which type of stem cells can only form closely related cell types?

Multipotent stem cells. Signup and view all the answers

What initiates the differentiation process of stem cells into specialized cells?

The interaction of morphogens with cell receptors. Signup and view all the answers

Which of the following statements is true about embryonic stem cells?

They give rise to all specialized cell types except an embryo. Signup and view all the answers

Which feature is NOT characteristic of stem cells?

They are specialized in function. Signup and view all the answers

What is a key feature of stem cell niches?

Niches help maintain and support the proliferation of stem cells. Signup and view all the answers

What is the characteristic feature of prokaryotic cells regarding their genetic material?

Their chromosome is present in a nucleoid region. Signup and view all the answers

Which of the following statements about eukaryotic plant cells is correct?

They contain a rigid cell wall. Signup and view all the answers

What is the primary function of mitochondria in eukaryotic cells?

Production of ATP through aerobic respiration Signup and view all the answers

In animal cells, where is the nucleus typically located?

In the center of the cell Signup and view all the answers

What distinguishes prokaryotic cells from eukaryotic cells?

Absence of membrane-bound organelles Signup and view all the answers

What is one feature that both animal and eukaryotic plant cells share?

Both have organized nuclei Signup and view all the answers

Which component is specifically found only in plant cells, enabling them to perform photosynthesis?

Chloroplasts Signup and view all the answers

What type of membrane structure is found surrounding the nucleus in eukaryotic cells?

Double membrane with pores Signup and view all the answers

What structural feature allows phospholipids to form a bilayer in water?

The hydrophobic tails repel water molecules. Signup and view all the answers

Which type of particles can freely pass through the phospholipid bilayer?

Hydrophobic uncharged particles. Signup and view all the answers

What is the primary reason for the efficiency of multicellular organisms compared to unicellular organisms?

Specialized tissues perform specific functions. Signup and view all the answers

What defines the direction of simple diffusion across a membrane?

From a region of high concentration to low concentration. Signup and view all the answers

Which statement accurately describes the movement of particles in kinetic theory?

Particles move in random directions at all times. Signup and view all the answers

What is the role of the phospholipid bilayer in cellular membranes?

To separate the cell contents from the external environment. Signup and view all the answers

Why is diffusion considered a passive process?

It occurs spontaneously without energy input. Signup and view all the answers

What is a key characteristic of amphipathic molecules like phospholipids?

They contain both hydrophobic and hydrophilic regions. Signup and view all the answers

Study Notes

Prokaryotic Cells

Prokaryotic cells contain a nucleoid region
Prokaryotic cells do not have a nucleus
Prokaryotic cells do not have a fixed regular shape

Eukaryotic Cells

Eukaryotic cells have a clear, visible nucleus
Animal cells do not have a cell wall
Plant cells have a cell wall
Plant cells have a fixed, regular shape

Prokaryotic Nucleoid Region

The chromosome of prokaryotes is located in the nucleoid region.
The prokaryotic chromosome is not associated with proteins
The prokaryotic chromosome contains the genetic information for the growth and development of the cell
The nucleoid region is visible as a lighter irregularly shaped region within the cytoplasm of the cell

Prokaryotic Cell wall

The prokaryotic cell wall is composed of peptidoglycan
The cell wall surrounds the cell
The cell wall is seen as a dark line around the outside of the cell
Underneath the cell wall is the plasma membrane

Eukaryotic Nucleus

The nucleus is a large structure found in the centre of animal cells
The nucleus is pushed up against the cell wall in plant cells
The nucleus has a double membrane with pores
The nucleus contains chromosomes
Chromosomes contain the genetic information for the growth and development of the cell.
RNA is produced in the nucleus

Mitochondria

Mitochondria have a double membrane
The outer membrane is smooth
The inner membrane is folded, creating cristae
Mitochondria produce ATP by aerobic respiration

Chloroplasts

Chloroplasts have a double outer membrane with many internal membranes
Chloroplasts are only found in plant cells that carry out photosynthesis
Chloroplasts contain chlorophyll
Chloroplasts are the site of photosynthesis

Multicellular Organisms

Multicellular organisms have specialized tissues
Specialized tissues carry out a range of functions
The specialized tissues allow for the more efficient use of resources
Multicellular organisms are larger than unicellular organisms
Multicellular organisms are better protected from predators
Multicellular organisms are capable of consuming smaller organisms

Phospholipids

A phospholipid is composed of two fatty acid chains and a phosphate bound to a glycerol molecule.
The fatty acid tails are nonpolar and hydrophobic
The phosphate head is charged and hydrophilic
Phospholipids are amphipathic, as they have both hydrophobic and hydrophilic regions

Phospholipid Bilayer

Phospholipids form a bilayer when added to water
The hydrophilic phosphate heads face the water
The hydrophobic fatty acid tails are in the middle of the bilayer
All membranes in cells are composed of a phospholipid bilayer

Plasma Membrane

The plasma membrane separates the cytoplasm and cell contents from the environment
The plasma membrane acts as a barrier to materials entering and exiting the cell
Only hydrophobic, uncharged particles can pass through the hydrophobic fatty acid tails at the centre of the bilayer
Large particles and charged, hydrophilic particles cannot pass directly through the phospholipid bilayer

Kinetic Theory

Particles are in constant motion
Particles in gases, liquids, and solutes in aqueous solutions move in random directions

Diffusion

Diffusion is the passive transport of a particle from a region of high concentration to a region of low concentration
It is called passive, because it uses no energy from the cell
Small uncharged particles (such as oxygen and carbon dioxide) can diffuse across plasma membranes.
Fat-soluble molecules (such as steroids) can diffuse across plasma membranes.

Neurotransmitter Gated Ion Channel

Acetylcholine is a neurotransmitter that opens sodium channels in the postsynaptic membrane of neurons
Acetylcholine is a ligand that attaches to a sodium ion channel
When acetylcholine is attached, the channel opens, allowing sodium ions to enter the neuron through the postsynaptic membrane.

Sodium Potassium Pump

The sodium potassium pump actively transports sodium ions out of a cell and potassium ions into a cell.
The sodium potassium pump maintains resting potential in neurons
The sodium potassium pump is an exchange transporter, as sodium and potassium ions travel in opposite directions.

Resting Potential and the Sodium Potassium Pump

Neurons are at resting potential (-70mV) when a nerve impulse is not being transmitted
The potential difference is maintained by sodium ions being outside the axon of a neuron, and potassium and chloride ions being inside the axon.
The sodium potassium pump transports sodium out of the axon and potassium into the axon
The sodium potassium pump transports sodium and potassium against their concentration gradients and is an example of active transport

Glucose Transport

Glucose is transported from the small intestine into the epithelial cells that line the intestine by two mechanisms:
Facilitated Diffusion: Glucose is passively transported through glucose channels from the small intestine into the epithelial cells.

Nuclear Membrane

The nuclear membrane breaks down at the beginning of mitosis and meiosis
The double membrane allows the nucleus to break down into many vesicles
At the end of mitosis and meiosis, the vesicles fuse to reform the nucleus

Ribosomes

Ribosomes synthesize polypeptides by translating mRNA
Ribosomes are composed of a large ribosomal subunit and a small ribosomal subunit
Both subunits are composed of proteins and ribosomal RNA

RER

Ribosomes can be floating free in the cytoplasm or attached to the rough endoplasmic reticulum
Free floating ribosomes synthesize proteins to be used in the cell
Ribosomes attached to the rough endoplasmic reticulum synthesize proteins to be transported out of the cell, or for the production of lysosome enzymes
The membrane of the rough endoplasmic reticulum is an extension of the nuclear membrane and is covered in ribosomes
Proteins produced by ribosomes attached to the rough endoplasmic reticulum enter the lumen of the rough endoplasmic reticulum
The proteins are packaged into vesicles which are transported to the Golgi apparatus

Golgi Apparatus

The Golgi apparatus is located between the rough endoplasmic reticulum and the plasma membrane
The Golgi apparatus is composed of flattened sacs known as cisternae
Vesicles containing proteins from the rough endoplasmic reticulum move to and fuse with the Golgi apparatus
The Golgi apparatus modifies proteins and packages them into secretory vesicles
Secretory vesicles move towards the plasma membrane and secrete the protein by exocytosis

Vesicles

Vesicles are composed of a phospholipid bilayer and transport materials around the cell
A protein called clathrin is involved in the formation of some vesicles
Clathrin is a triskelion-shaped protein that attaches to recruiter proteins in a membrane, forming a vesicle
The clathrin proteins polymerise to form a clathrin cage, forcing the membrane to form a rounded bud
This bud is cleaved off to form a clathrin-coated vesicle
The clathrin cage is then removed

Fertilization

Fertilization is the fusion of gametes
The fusion of gametes leads to the development of a zygote
The zygote is a totipotent stem cell

Totipotent Stem Cells

Totipotent stem cells can develop into all other cell types or develop into an embryo

Embryonic Stem Cells

The zygote develops into a blastocyst through cell division over five days
The blastocyst contains embryonic stem cells
Embryonic stem cells are pluripotent meaning that they can differentiate into all other cell types but not into an embryo

Cell Differentiation

All cells from a multicellular organism have the same genome
Stem cells differentiate into specialized cells by expressing some genes and not expressing others

Adult Stem Cells

The blastocyst develops into a fetus, as the embryonic stem cells differentiate into specialized cells
Some adult stem cells remain to replenish dying cells and repair damaged tissue
Most adult stem cells are multipotent, meaning that they can form a range of closely related cells
Hematopoietic stem cells are multipotent, as they can differentiate into all types of blood cells, but not other cell types

Embryonic Development

Embryonic stem cells differentiate into specialized cells and tissues in a controlled manner through a group of gene regulating chemicals, known as morphogens
Morphogens are a group of gene regulating chemicals that determine the specialized cell that develops according to their concentration
Morphogens are produced and released from embryo cells and diffuse through tissues
Morphogens spread, creating a concentration gradient across tissue, with the highest concentration near the source
Morphogens bind to receptors on cells, resulting in the activation or repression of genes
The concentration of the morphogen determines which genes will be expressed, determining the type of specialized cell

Stem Cells

Stem cells are undifferentiated cells
Stem cells have an unlimited capacity to divide
Stem cells can differentiate into specialized cells

Stem Cell Niche

Adult stem cells are located in stem cell niches
Stem cell niches are locations in the body where stem cells can be maintained or promoted to proliferate and differentiate

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Description

This quiz covers the key differences between prokaryotic and eukaryotic cells, focusing on their structures, functions, and components. It also explores details about the nucleoid region of prokaryotes and the role of the nucleus in eukaryotic cells. Test your understanding of cellular biology concepts.