C5.1: Membrane-bound Flashcards by Jasmine Marta

are cellular structures that are enclosed by a biological membrane, typically consisting of a single or double layer of lipids with interspersed proteins.

Membrane-bound organelles

How well did you know this?

Not at all

Perfectly

Most of these organelles within cells are indeed filled with a fluid, and these organelles are enclosed by a ___ to create a distinct internal environment separated from the rest of the cytoplasm

plasma membrane

How well did you know this?

Not at all

Perfectly

serve as physical barriers that enclose the contents of membrane-bound organelles, effectively isolating them from the surrounding cytoplasm.

Lipid bilayer membranes

How well did you know this?

Not at all

Perfectly

are selectively permeable, meaning they control the passage of ions, molecules, and proteins in and out of organelles

Lipid bilayers

How well did you know this?

Not at all

Perfectly

help establish and maintain distinct chemical environments within organelles

Membranes

How well did you know this?

Not at all

Perfectly

help organize cellular processes by segregating enzymes, substrates, and reactants into specific compartments; this spatial organization enhances the efficiency and coordination of biochemical reactions.

Membranes

How well did you know this?

Not at all

Perfectly

membrane-bound organelles (9)

Nucleus
Endoplasmic Reticulum
Mitochondria
Chloroplasts
Golgi Apparatus
Lysosomes
Peroxisomes
Secretory Vesicles
Vacuole

How well did you know this?

Not at all

Perfectly

Function of ___ is the biosynthesis of ribosomal RNA and production of ribosomes

nucleolus

How well did you know this?

Not at all

Perfectly

largets organelle; control center; regulate gene expression

Nucleus

How well did you know this?

Not at all

Perfectly

site of cellular chemical reactions

How well did you know this?

Not at all

Perfectly

The ER is composed of a series of highly folded membranes called ___.

cisternae

How well did you know this?

Not at all

Perfectly

Ribosomes are scattered across cisternae

Rough ER

How well did you know this?

Not at all

Perfectly

___ are responsible for synthesizing polypeptides, which are subsequently either integrated into the membrane of the Rough Endoplasmic Reticulum (RER) or transported into the lumen, the central region, of the cisternae.

Ribosomes

How well did you know this?

Not at all

Perfectly

it is where proteins are generated in the rough ER.

lumen of cisternae

How well did you know this?

Not at all

Perfectly

Consist of interconnected membranous sacs without ribosomes; enzymes found either bound to the surface of this ER or situated within its cisternae.

Sooth ER

How well did you know this?

Not at all

Perfectly

responsible for the transport of synthesized proteins; helps with the protein folding

Smooth ER

How well did you know this?

Not at all

Perfectly

a process where sugar molecules are added to proteins or lipids.

Glycosylation-

How well did you know this?

Not at all

Perfectly

double-membrane-bound, spherical or rod-shaped organelles

mitochondria

How well did you know this?

Not at all

Perfectly

The term ‘mitochondrion’ is derived from the Greek words “___” and “___” which means “__” and “__”, respectively.

mitos (thread); chondrion (granules-like)

How well did you know this?

Not at all

Perfectly

carry out oxidative phosphorylation; production of energy through ATP synthesis

Mitochondria

How well did you know this?

Not at all

Perfectly

site for synthesizing food by the process of photosynthesis

chloroplast

How well did you know this?

Not at all

Perfectly

Golgi apparatus is primarily made up of stacked, flattened pouches known as ___.

cisternae

How well did you know this?

Not at all

Perfectly

Protein packaging and secretion; transportation; participate in the production of lysosomes

Golgi Apparatus

How well did you know this?

Not at all

Perfectly

It digests dead and damaged cells, aids in digestion, and eliminates waste; “suicidal bags”

Lysosomes

How well did you know this?

Not at all

Perfectly

are small organelles containing enzymes, primarily serve as the primary sites for intracellular digestion in cells.

Lysosome

Functions of lysosome (3)

Autophagy Heterophagy Biosynthesis

__: The digestion of cellular components and organelles from within the cell, allowing for recycling and the reuse of nutrients

Autophagy

: The digestion of external materials that are taken into the cell, such as nutrients acquired from the environment or particles ingested through processes like phagocytosis.

Heterophagy

: Involves recycling and processing unwanted or damaged cellular components and products of chemical reactions, contributing to the cell's overall metabolic processes.

Biosynthesis

degradation of long-chain fatty acids by beta-oxidation; Breakdown of toxic compounds

Peroxisome

prominently associated with processes like fatty acid oxidation, detoxification of harmful compounds, and the synthesis of certain lipids called ___.

peroxisome; plasmalogens

involved in the transport and delivery of molecules like hormones or neurotransmitters, either into or out of the cell.

Secretory Vesicles

___ is the mechanism by which the contents of secretory vesicles are moved out of the cell. During this mechanism, these vesicles fuse with the cell membrane, releasing their contents into the extracellular space.

Exocytosis

__ is the process of moving the contents of secretory vesicles into the cell. This occurs when the cell membrane engulfs and internalizes external materials or molecules by forming vesicles.

Endocytosis

essential cellular structures found primarily in plant cells; maintaining turgor pressure or turgidity within the cell

Vacuole

results from the osmotic movement of water into the vacuole, causing the cell to become swollen and pushing the plasma membrane against the rigid cell wall.

Turgor pressure

Its structure consists of a network of interconnected membranous tubules, vesicles, and cisternae, which together form an extensive, intricate system throughout the cell.

The endoplasmic reticulum (ER) is a vital organelle in eukaryotic cells, responsible for a variety of cellular functions, including (4)

protein synthesis lipid synthesis calcium storage detoxification

main function RER

protein synthesis

main function SER (3)

Lipid metabolism, detoxification, and calcium storage

Proteins destined for the Endoplasmic Reticulum (ER) are typically inserted into the ER membrane ___

co-translationally

signal sequence is usually located at the __ of the protein.

N-terminus

signal sequence is recognized by a complex called the ___

Signal Recognition Particle (SRP).

As proteins are synthesized on the ribosomes, they are modified and folded into their correct three-dimensional structure

PROTEIN PROCESSING

The ___also serves as a site for quality control in protein synthesis. It checks whether the synthesized proteins are correctly folded. Misfolded or improperly assembled proteins are targeted for degradation.

Rer

After their synthesis and processing in the RER, proteins are transported to their target destinations

TRANSPORT

Many proteins synthesized in the RER are ___, meaning they are destined for export out of the cell.

SECRETORY PROTEINS

___ is the process in which ribosomes in the cytoplasm or ER synthesize proteins after the process of transcription of DNA to RNA in the cell's nucleus. The entire process is called ____

Translation; gene expression

Translation proceeds in three phases

Initiation: Elongation Termination

The ribosome assembles around the target mRNA. The first tRNA is attached at the start codon.

Initiation:

The tRNA transfers an amino acid to the tRNA corresponding to the next codon. The ribosome then moves (translocates) to the next mRNA codon to continue the process, creating an amino acid chain.

Elongation:

When a peptidyl tRNA encounters a stop codon, then the ribosome folds the polypeptide into its final structure.

Termination:

Eukaryotes undergo translation in the cytosol or on the endoplasmic reticulum (ER) membrane in a process known as __

co-translational translocation

During ____, the ribosome-mRNA complex attaches to the ER's outer membrane, allowing newly synthesized proteins to enter the ER.

co-translational translocation

refers to the covalent and generally enzymatic modification of proteins following protein biosynthesis

Post-translational modification (PTM)

Post-translational modifications can occur on the amino acid side chains or at the protein's ___

C- or N- termini

Attachment of lipid molecules, known as ___, often targets a protein or part of a protein attached to the cell membrane

lipidation

___ is one example that targets the modified protein for degradation and can result in the formation of protein aggregates

Carbonylation

The SER is involved in ____, which encompasses the synthesis and modification of lipids

lipid metabolism

SER plays a pivotal role in breaking down ___ (foreign substances)

xenobiotics

One group of enzymes found in the SER, called ___, is particularly important in drug metabolism

cytochrome P450 enzymes

there is an insufficient supply of oxygen in the cell, a condition known as __ ER may struggle to support oxygen-dependent processes.

Hypoxia

In cases of low glucose levels, ER may experience a shortage of energy

Hypoglycemia

High temperatures, can alter the chemical reactions taking place in the ER. Proteins may become denatured or misfolded due to excessive heat, leading to protein aggregation and ER stress.

Hyperthermia

acidic environment within the cell or ER can disrupt the normal pH balance required for enzymatic reactions and protein folding

Acidosis

Changes in calcium ion concentrations can disturb the ER's calcium homeostasis and lead to disruptions in protein folding and transport

Calcium Ion Levels

refers to the balance between oxidized and reduced molecules within the cell, is crucial for various cellular processes, including protein folding

Redox State

often modulated by hypoxia and hypoglycemia, can compromise the ER's ability to perform tasks such as protein synthesis and proper protein folding.

Reduced energy levels

FACTORS THAT CAN CONTRIBUTE TO ER STRESS (7)

-HYPOXIA -HYPOGLYCEMIA -HYPERTHERMIA -Acidosis -Changes in calcium ion levels -Reduced energy levels -ALTERED REDOX STATE

Cellular Response to ER Stress (4)

1. Unfolded Protein Response (UPR) 2. Proteotoxic Threat and Protein Clearance 3. ER Lumen Dilation 4. ER Stress Response

___ is a set of signaling pathways and cellular processes that aim to restore ER function and alleviate the stress. It involves a complex network of molecular events that are activated in response to the accumulation of unfolded or misfolded proteins within the ER lumen

UPR Unfolded Protein Response

damaged proteins are exported from the ER to the cytoplasm and then targeted for degradation by the proteasome, a cellular protein disposal system

ER-associated degradation (ERAD),

damaged proteins are compacted together with other cellular debris into juxtanuclear complexes. These complexes are then recycled via autophagy, a cellular mechanism for the recycling of surplus or defective cellular components

aggresome formation

involves an expansion of the ER's internal compartments, creating a larger lumen or internal space

ER Lumen Dilation

The primary purpose of this expansion is to accommodate the increasing load of proteins and other lumenal constituents that are being synthesized to manage ER stress.

ER Lumen Dilation

The ___ is a dynamic system that can lead to either adaptation or apoptosis, depending on the severity of the stress and the cell's ability to cope with it.

ER stress response

This module triggers a series of events that ultimately lead to cell death (apoptosis).

proapoptotic module

also known as microbodies; Made up of a phospholipid bilayer and crystalloid core which is not always present

peroxisome

While lysosomes break down proteins, peroxisomes break down fatty acids. Which is known as ___

lipid catabolism.

___ also known as free radicals like oxygen ions which is a byproduct of normal cellular respiration, radiation, tobacco, or drug

reactive Oxygen Species ROS molecules

Peroxisomes: Metabolize chain of very long chain fatty acids via ___. Metabolize branched chain of fatty acids via __.

beta-oxidation; alpha-oxidation

___ is a myelin sheath that covers the nerve.

Plasmalogen

peroxisomes contain ___ that breaks down hydrogen peroxide into water and oxygen.

catalase

Peroxisomal disorder that is Autosomal recessive, both parents are carriers of the gene, specifically the gene called PEX gene.

Zellweger Syndrome

___ is important because it codes for proteins called peroxins that are essential in making peroxisomes.

PEX gene

In order for a protein to get into the peroxisome, it needs to have a targeting signal called the ___

peroxisomal targeting signal

Types of Protein Targeting Signals in peroxisome (3)

-PTS1 -PTS2 -PMP

- takes protein in the lumen of the peroxisome

PTS1

- helps protein to get integrated inside the membrane of the peroxisome

PMP

Zellweger's syndrome is caused by mutations in any of 13 of the 14 PEX genes, mostly in ___

PEX1