Mammalian fertilization comprises sperm migration through the female reproductive tract, biochemical and morphological changes to sperm, and sperm-egg interaction in the oviduct. Recent gene knockout approaches in mice have revealed that many factors previously considered important for fertilization are largely dispensable, or if they are essential, they have an unexpected function. These results indicate that what has been observed in in vitro fertilization (IVF) differs significantly from what occurs during “physiological” fertilization. This Review focuses on the advantages of studying fertilization using gene-manipulated animals and highlights an emerging molecular mechanism of mammalian fertilization.
The human brain consumes up to 20% of the energy used the entire human body which is any other single organ. the brain represents inly 2%of the body wheight yet it recieves 15% of the cardiac output and 20% of the total body oxygen consumption.
Answer:
Electron transport chain and ATP synthase
Explanation:
The inner mitochondrial membrane contains an electron transport chain and ATP synthesis. Four membrane protein complexes serve as the electron carriers and are embedded in the inner mitochondrial membrane. These protein complexes are called complex I, II, III and IV. Transfer of electrons from NADH and FADH2 to terminal electron acceptor oxygen occurs via these protein complexes.
During electron transfer, the pumping of protons towards the inner mitochondrial membrane creates an electrochemical gradient. The downhill transfer of protons back to the matrix via proton channel of ATP synthase drives phosphorylation of ADP. Therefore, presence of all the protein complexes of the electron transport chain and ATP synthase is required for electron transfer and ATP synthesis.
There are several types of changes that could happen. If one of the
letters of DNA were to be changed to a differnt letter, this might
result in a differnt amino acid being put into the protein being
synthesized. Or, changing a single letter could tell the protein to
stop being made (a stop codon is formed) this would make a much smaller
version of the protein. If a letter is either inserted or deleted this
is called a "frame shift" mutation and this totally destroyes the
message. A sudden change in the sequence of DNA could also "silence"
the gene turning off transcription so that no mRNA would even be made.
Or, it could enhance transcription increasing the ammount of mRNA.
There are many many ways that a DNA mutation can affect mRNA, do you
need anything more specific?<span>Its
very simple,mRNA is kinda messenger which takes information from
genetic material(DNA) which will later get translated to functional
protein.The information in genetic material is in the shape of sequence
of nucleotides pairs.there are four kinda nucleotides
1.adenine,2.guanine3.cytosine4.thiamine.... nucleotides lare kinda codes
which get imprinted on mRNA , where thiamine is exception coz it get
transcribed to uracil.
,since mRNA does contain thiamine but it has a replacement known as
uracil.So its very simple if there will be any change in nucleotide the
information given to mRNA will also change .So u see sudden change in
nucleotides will mean that information send to mRNA will get
changed.other things getting affected would be protein.</span><span>.As mRNA will later translate this information to make proteins from amino acids</span>
More variation assists with survival. It increases the chance that at least some offspring of a parent survive.
