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Andre45 [30]
3 years ago
15

Modern humans first appeared during the

Biology
2 answers:
stira [4]3 years ago
4 0
A. Most recent period of the Cenozoic era. 


ratelena [41]3 years ago
4 0

Answer:

The correct answer is A) most recent period of the Cenozoic era.

Explanation:

Modern humans belong to a species called Homo sapiens that first appeared approximately 200.000 years ago. The Cenozoic era is the latest, made of two periods (tertiary and quaternary) where the latest is the quaternary that goes from 1,8 to 0,01 million years.

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How does the structure of a brain cell related to its function?
lesya [120]

Solution:

Structure dictates function. Ribosomes provide another good example of structure determining function. These small cellular components are made of protein and ribosomal RNA (RNA).Their main function is to translate messenger RNA, or mRNA, into strings of amino acids called proteins.

The structure and shape of each type of human cell depends on what function it will perform in the body. For example, red blood cells (RBCs) are very small, flat discs, which allows them to easily fit through narrow capillaries and around sharp corners in the circulatory system to deliver oxygen throughout the body.

Neurons carry messages from the brain and spinal cord to the rest of the body, using electrical signals down their lengths and chemical signals between neurons. Since electrical signals travel much faster than chemical signals, neurons are long and thin to minimize the number of slower chemical signals that would be required between links in a chain of many shorter neurons.

The elongated shape of muscle cells allows the contraction proteins to line up in an overlapping pattern that makes muscle flexing possible.

And human sperm cells’ structures allow them to “swim” long distances to reach an egg for fertilization. They do this by using flagella, their long whip-like tails, and also by being very small, carrying little more than the DNA for a potential zygote.

This is the required answer.

7 0
3 years ago
you notice a sign in a parking structure that says "Warning: This area contains chemicals known to the state of California to ca
Brrunno [24]
They can enter your blood stream (via breathing/ingesting) and once in your bloodstream they can enter cells and mutate your dna, which can cause cancer/birth defects/ reproductive harm
4 0
3 years ago
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2 years ago
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Ras is a g-protein that is activated when a growth factor attaches to egfr. its activation results in the replacement of a gdp m
kodGreya [7K]

Answer:

A mutation in Ras protein which will cause hyperactivity will eventually lead to cancer.

Explanation:

Ras protein was first discovered in Rous sarcoma virus (RSV) and it is a proto-oncogene product. In normal conditions, it plays an important role in cellular signalling but in case of gain of function/hyperactivity it gets converted into cellular oncogene. In several types of cancers a point mutation has been reported in Ras protein.

Just like G protein, it is also a GTPase switch protein but unlike G protein which is trimeric, it is monomeric. In the plasma membrane, it is attached with the help of lipids like prenyl or palmitoyl groups. During signal transduction pathway when it gets activated, it downstream activates MAPK pathway and causes gene expression but when it gets hyperactivated it causes over expression of genes leading to cancer.

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2 years ago
if a homozygous dominant parent and a heterozygous parent are crossed, what percentage of the offspring are expected to be heter
Arada [10]
50%..................
8 0
3 years ago
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