Created by Ross Firestone.
Watch the next lesson: https://www.khanacademy.org/test-prep/mcat/biomolecules/genetic-mutations/v/the-causes-of-genetic-mutations?utm_source=YT&utm_medium=Desc&utm_campaign=mcat
Missed the previous lesson? https://www.khanacademy.org/test-prep/mcat/biomolecules/genetic-mutations/v/an-introduction-to-genetic-mutations?utm_source=YT&utm_medium=Desc&utm_campaign=mcat
MCAT on Khan Academy: Go ahead and practice some passage-based questions!
About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.
For free. For everyone. Forever. #YouCanLearnAnything
Subscribe to Khan Academy’s MCAT channel: https://www.youtube.com/channel/UCDkK5wqSuwDlJ3_nl3rgdiQ?sub_confirmation=1
Subscribe to Khan Academy: https://www.youtube.com/subscription_center?add_user=khanacademy
shishi Rad You asked this a long time ago but I don’t know if you ever got your answer. Remember DNA molecules are ~<1,000,000 base pairs long, so if a frame shift mutation occurs closer to the start codon, its effect will be greater than if it had been closer to the Stop codon. Codons are always 3bp long, so in the example the G wasn’t translated only because he didn’t have a longer sequence. So in actual DNA, the codons will keep being translated and transcribed until it reaches a stop codon.
I don't think silent mutations are a subset of missense mutations as you've mentioned.
Silent mutations are a part of synonymous mutations; nonsynonymous encompasses missense mutations (which can be conservative/non-conservative), nonsense mutations, and stop-loss mutations (where the stop codon is changed for a coding codon).
Point mutation is a change in a single nucleotide of a codon, this affects the structure of DNA but the effect it will have in the resulting protein is not specified yet, hence there are several types of point mutation that describe what effect it will have in the protein.
Kahn Academy has been valuable to me in many areas of my education, but these videos in particular are terrific, because the PACE is right for me. I actually learn better if the video moves along more quickly.
Do not interpret them as "different." Rather, missense mutation is a classification of point mutation. There are several ways of picturing point mutations and from an analytical perspective, we first look at their category, then classification.
There are more information on mutation than this video covered, and this just an overview on point mutation itself. Get a copy of Lewin Genetics or any molecular genetics textbook really to find out more.
Just as others have pointed out, point mutations were oversimplified.
But more concerning is the lac of other very common mutations:
2. Mutations that do not change protein structure, but rather its copy number (non coding mutations)
3. Deletions can be frame shift and non frameshift
4. Insertions : also frame shift and non frame shift
5. Trinucleotide repeat expansions (fragile x syndrome)
6. Epigenetic silencing or up regulations -- not mutations in the traditional sense, but more commonly recognized as mutations in the "histone code"
-- and maybe more im not thinking of on top.
Yes i see now how its possible XD I asked my bio teacher after posting this, and she said that insertion and deletion will always result in a frame shift. But I can assume that that's just what she wanted us to understand for now.
+S Parker , one possibility is a deletion in a non-coding portion such as an intron or promoter region.
These areas control various aspects about how a genetic sequence is treated by the nuclear machinery, but they do not actually get transcribed... Or if they get transcribed, they are not translated...therefore no codons, therefore, no frameshift.
--frameshift refers to how codons are read during translation.
A point mutation is a classification of mutations in which a single codon is substituted. Classically point mutations have three types. Silent mutation is where the third codon (wobble position) is changed but the resulting amino acid does NOT change. This brings up the concept of redundancy. The other types of point mutations are missense (one amino acid changed) and nonsense (premature stop codon) which were termed in the video. Frameshift can be described as a point mutation (insertion or deletion of one codon), but typically textbooks will make a clear distinction between point and frameshift mutations. Two years later, hope that helped lol
Antidepressants are medications that can help relieve symptoms of depression, social anxiety disorder, anxiety disorders, seasonal affective disorder, and dysthymia, or mild chronic depression, as well as other conditions.
They aim to correct chemical imbalances of neurotransmitters in the brain that are believed to be responsible for changes in mood and behavior.
Depression Medications (Antidepressants)
These are the most commonly prescribed type of antidepressant.
Serotonin and noradrenaline reuptake inhibitors (SNRIs) are used to treat major depression, mood disorders, and possibly but less commonly attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety disorders, menopausal symptoms, fibromyalgia, and chronic neuropathic pain.
SNRIs raise levels of serotonin and norepinephrine, two neurotransmitters in the brain that play a key role in stabilizing mood.
Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed antidepressants. They are effective in treating depression, and they have fewer side effects than the other antidepressants.
SSRIs block the reuptake, or absorption, of serotonin in the brain. This makes it easier for the brain cells to receive and send messages, resulting in better and more stable moods.
They are called "selective" because they mainly seem to affect serotonin, and not the other neurotransmitters.