|
SCIENCE FINALL!!!
ugh ok im kind of having a moment and i cant remember anything for science.
-PLEEEASE someone tell me the different between a crop and gizzard in an earthworm
-what is a closed and open circualtory system???
-what do mRNA, rRNA, and tRNA do???
im really sorry these questions are so sdfkjsfj but our books had to be checked in friday or else i could have looked the answers up in them.
thank you SO MUCH!!!
[ ]
Want to answer more questions in the Work & School category?
Maybe give some free advice about: School?
Gotcha taken care of.
CROP - part of the digestive system where food can be stored
GIZZARD - part of the digestive system where food is grounded into smaller pieces
The digestive track of an earthworm goes pharynx-crop-gizzard. So it stores food in the CROP (kinda like our stomach) and then grinds it up into smaller pieces in the gizzard.
Here are the official definitions for closed and open circulatory systems.
OPEN CIRC SYSTEM - system in which blood is not always contained within a network of blood vessels.
CLOSED CIRC SYSTEM - system in which blood is contained in a network of blood vessels.
Most advanced animals have a CLOSED CIRC SYSTEM because it allows blood to be transferred through the body quicker, allowing for more oxygen to be spread, allowing for the animal to move around more.
mRNA, rRNA and tRNA are more confusing, though, so I'll try to go slow.
mRNA = messenger RNA
rRNA = ribosomal RNA
tRNA = transfer RNA
DNA has to copy itself in order to go through meosis and mitosis. I assume you know what those are...you can message me if you're unsure. DNA replicates by an enzyme (DNA polymerase) that breaks the hydrogen bonds that hold the nitrogen bases together. The process continues until everything has been "unzipped."
DNA is only found in the nucleus and proteins are assembled outside of the nucleus. RNA must copy the DNA strand and carry it outside the nucleus to the rest of the cell.
As enzymes "unzip" the DNA, free RNA nucleotides pair with DNA nucleotides (DNA ADININE-URACIL; THYMINE - RNA ADININE; GUANINE - CYTOSINE) when the base pairing is finished, these *mRNA* break away and leave the nucleus.
Proteins need to be made from the mRNA copy of DNA, so...
The first codon of mRNA attaches the ribosome. Then tRNA molecules with teh correct anti-codon attach to the mRNA strand. The mRNA sidles along the ribosome to the next codon. When the first and second aminio acids are in place, an enzyme forms a bond between them. They continue until a certain code in the mRNA strand stops. This takes place in the rough endoplasmic reticulum.
rRNA is the ribosomal RNA. Ribosomes are made of several dozen proteins.
:-)
Hope that helps.
]
all i remember is:
mRNA is messenger rna
rRNA is ribosomal rna
tRNA is transfer rna
haha. there you go. asking google will help too.
]
More Questions: |