what's going on bessies today we're going to be tackling the t7 science portion specifically life and physical science and we're going to be talking about cell structure function and organization let's get started so when we think about biological systems they're structured across multiple layers each one is integral to understanding the entirety of life processes the first level that we're going to explore is the cell it's the most Elementary unit of life but is there anything smaller than a cell well yes indeed there is within cells that house organel these organel are smaller than the cells themselves moreover we have biomolecules which play crucial roles within the cell and are tinier than the cells themselves and even further down as we have atoms we can break those down further into subatomic particles which are again even smaller than the cells however for the te's we're going to begin at the cellular level which is the fundamental unit of life this is the universal truth regardless if you're a bacterium a fungus protus plant or animal all living things are going to be Cellular in nature when these numerous cells collaborate to perform unified functions they form what is known as tissues marking the subsequent level of biological organization cardiac muscle tissue for example consists of cardiac muscle cells working in concert together to make our heartbeat these tissues can then combine to compose organs representing that third tier of our hierarchy of biological structures your body is composed of numerous organs such as your heart your lungs and your kidneys when these organs collaborate inside of our body they are going to form what we call an organ system let's take the digestive system for example it encompasses various organs including our stomach our small intestine large intestine and liver they all work together in harmony to Aid the digestion of food and the conversion of that food into energy necessary for cellular processes the digestive system is merely one instance of an organ system when you interconnect all of these organ system together what emerges an individual an organism just like you there are additional biological hierarchies including population community ecosystem biomes and biosphere but for the purposes of the aits this is the group that you should focus on our first practice question is in the context of biological organization which of the following sequence correctly orders the hierarchy from simplest to the most complex is it A B C or D and the correct answer is a cells tissues organ organ systems and organisms as we know the correct answer is always going to start with our cells that's the basic unit of Life cells group together to form tissues which combine to create organs these organs work together in organ systems and then of course multiple organ systems are going to create the organism that is what we are our next question states which statement accurately describes the relationship between organ systems and organisms in biological hierarchy is it a organ systems exist independently of organisms and do not interact with each other is it B an organism is composed of multiple cells bypassing the need for an organ system is it C organ systems are composed of organs that work independently to support an organism's life or is it D organisms are comprised of multiple organ systems working together to ensure survival and the correct answer is D organisms are comprised of multiple organ systems working together to ensure survival if these systems did not work together we wouldn't really survive very long so yes the correct answer is going to be D now that we have a basic understanding of biological hierarchy let's get down and dirty when it comes to cells modern cell theory encompasses several key principles firstly it states that cells represent the most fundamental unit of life across all organisms secondly it asserts that every living entity is composed of cells which may be singular like we see with bacteria which is a unicellular organism or could be made up of multiple cells making them multicellular like humans the third principle states that cells arise only from existing cells highlighting their capability to replicate when you think about it cells are complex entities that house genetic material and are capable of division they have internal structures or organel that perform various functions and processes on Earth cells are categorized by two principal types reflecting the diversity of life's cellular foundations within the cellular world you are classified as either procaryotes or ukar bacteria and ARA all both fall within the procaryote category while fungi protus animals and plants all fall within the ukar category both of these categories share common features such as genetic materials cytoplasm and ribosomes each are small organel responsible for protein synthesis additionally they both have cell membranes that regulate the passage of substances in and out of the cell however the distinction between them is pretty significant procaryotes suggest that with the prefix pro meaning no that's going to be a memory trick for you to remember for the aits is that they lack a nucleus that houses and manages genetic information furthermore they do not have membranebound organel which are more complex structures like a nucleus mitochondria and ggia apparatus like we find with our UK carot cells so whenever I'm trying to remember which one has a nucleus and which one has membrane bound organel I use this pneumonic Pro means no which means they don't have those and u means do which means that they do have those you might now be curious about the roles of organel what functions do they serve well let's begin by talking about the cell membran also referred to as the plasma membrane this barrier has selective permeability which means that it allows only specific materials in and out of the cell The Selective entry and exit Point helps maintain stability within the cell and state known as homeostasis once we get inside the cell we are immersed with a jellylike substance known as the cytoplasm this substance envelops all of the cells internal structures and it's present in both procaryotes and ukar contrary to what one might assume the organel floating within the cytoplasm receive substantial support this support comes from the cyto skeleton it's an intricate network of fibers that not only provides structural support for the cell but it also plays a crucial role in cellular movement navigating our way through the cytoplasm we encounter ribosomes first notably ribosomes are not enclosed by membranes and are found in both procaryote and eukaryot cells their primary function is protein synthesis this is a critical process since a significant portion of genetic material also known as DNA is dedicated to cating for proteins ribosomes May either float freely within the cytoplasm or it can be anchored to another organel which is a topic we're going to discuss very soon shifting our attention to organel exclusive to UK carots we now explore those that are encased in membranes this ultimately brings us to our key player the nucleus often considered the control center of eukariotic cells it's here within the nucleus that our DNA is housed and stored while all cells do possess DNA in UK carots it's neatly contained inside the nucleus the nucleus oversees the cell's operations and houses the nucleos which is a specialized area where ribosomes are assembled next up the endoplasmic reticulum adjoining to the nucleuses membrane or nuclear envelope plays a crucial role in the cell's operation this organel is going to be instrumental in processing molecules such as the folding of proteins and serves as the primary conduit when it comes to transporting throughout the cell much like a cellular Highway the endoplasmic reticulum comes in two forms we have rough ER which is studed with ribosomes lending to the name rough in its appearance and we have smooth ER which is going to lack those ribosomes the ruar is particularly active in the synthesis and transport of proteins it's a direct consequence of its association with ribosomes which are the cellular Machinery responsible for protein synthesis molecules exiting this ER is often enclosed in vesicles that bud from the ER itself on the other hand our smooth ER has a much broader range of functions including detoxification which is a vital process especially abundant in liver cells due to their high content of having smooth ER additionally to detoxification the smooth ER is involved in synthesis of certain types of lipids further diversifying its functional portfolio moving on to the gold G apparatus often regarded as the cell's Premier packaging and Distribution Hub it accepts materials from transport vesicles that have detached from the ER employing enzymes to modify these receiving molecules and organ izing them accordingly the Gogi apparatus also decides the destination of these molecules including directing some of the cell membrane for secretion effectively expelling them from the cell amidst all of these cellular activities that are taking place you might begin to question what exactly is fueling them enter the mighty monoch condriac ATP energy through a process known as cellular respiration unlike conventional power plants mitochondria operates on glucose it's a type of sugar and requires oxygen to produce ATP energy efficiently in addition to mitochondria plant cells boast remarkable organel known as chloroplasts chloroplasts are capable of synthesizing glucose through the process of photosynthesis which harnesses light energy their green appearance is attributed to the pigment that they absorb from light energy reflecting green light back giving plants their colorful characteristic lomes often dub the cell's waist deposal system are membranebound organel filled with enzymes that break down biomolecules such as proteins lipids and carbohydrates they play a crucial role when it comes to digesting cellular debris unwanted materials as well as invasive organisms like bacteria maintaining cellular cleanliness and recycling materials that are reused by the cell vacul on the other hand are large fluid-filled saxs find predominantly in plant cells though they are also present in some animal and fungal cells their functions are going to vary including storing nutrients and waste products to maintaining internal hydrostatic pressure within the cell and sequestering harmful materials in plants vules are pivotal when it comes to growth because they absorb water and expand enabling the cell to grow larger with minimal investment of new biomass now let's do some practice on everything we just learned which of the following cell components is primarily responsible for assembling proteins using instructions encoded in mRNA is it the nucleus ribosomes gogia apparatus or mitochondria and the correct answer is B our ribosomes so again ribosomes are those cellular structures responsible for protein synthesis so they actually read the sequence of mRNA and assemble amino acids into proteins based on what was coded in the instructions the nucleus houses that DNA the gogia apparatus modifies and packages the proteins and the mitochondria are involved in energy production But ultimately it's those ribosomes they're going to be directly related to synthesizing proteins which organel is known as the PowerHouse of the cell due to its role in producing ATP which is the cell's main energy currency is it the coroplast the nucleos mitochondria or endoplasmic reticulum and the correct answer is C mitochondria like we talked about before that mitochondria is responsible for producing ATP also known as adenosine triphosphate they do this through a process of cellular respiration which is why they're often referred to as the powerhouse of the cell our chlorop paaths are involved in photosynthesis when it comes to plant cells our nucleos is involved in ribosome production inside our nucleus and of course our endoplasmic reticulum is involved in protein and lipid synthesis as well as processing I hope that this video is helpful in understanding cell structure function and organization as always if you have any questions make sure that you leave them down below I love answering your questions head over to nurse chunk store.com where there's a ton of additional resources that are available to you to help you Ace those ait's exams and as always I'll catch you in the next video bye