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A&P Lecture 17
| Question | Answer |
|---|---|
| Genes are discreet segments of | DNA |
| Each gene contains information about | a certain trait |
| Genes are _______ into RNA, RNA is ______ into a protein | Transcribed Translated duh |
| On a chromosome, genes are organized into segments of | exons and introns |
| Both exons and introns are transcribed into | RNA |
| Exons are the segments that | do code for a protein |
| Introns are the segments that | do not code for a protein 98% of human DNA does not code for a protein |
| These non-coding DNA segments were once thought of as junk DNA but are known to function in a process called | alternative splicing |
| Alternative splicing | is a cellular process in which exons from the same gene are joined in different combinations a post transitional modification allowing for increased diversity |
| 1 gene can generate different | mRNA transcripts |
| Each mRNA transcript can be translated into a | slightly different protein |
| These different protein structures will have | slightly different functions. ALL FROM A SINGLE GENE |
| **There is one additional component of a gene that informs when and where to express the gene (make protein) | |
| Promoter regions | a region of the gene upstream of protein coding region |
| **Recall: All nucleated cells contain the same genetic material inside nucleus | |
| Promoters ensure that | Genes are transcribed at different levels for different tissues By varying gene expression, cells can adopt a wide range of functions |
| In humans, mutations to the promoter regions are associated with (3) | Parkinson's disease Alzheimer's disease Various cancers |
| changes to DNA sequence can alter | protein function |
| Wild type | reverse to the common, typical, genetic sequence of individuals in natural conditions Clinical, these are called healthy controls! |
| A mutation is | an alteration in the nucleic acid sequence of the genome of an organism. This results in creation of a mutant gene |
| **Alterations to the DNA sequence (mutation) will cause changes to RNA sequence, which may change amino acid sequence of the protein | |
| Silent mutations | change DNA, but amino acid is unchanged. Protein function is normal Best to have |
| Nonsense mutations | change DNA to transcribe a premature stop codon. This greatly reduces protein function and is very disruptive Worst to have |
| Missense mutations: | A single base pair change (substitution) leading to a different amino acid. The degree in which this alters protein function depends on where in the protein this takes place and by what amino acid switched Varies on how bad it is |
| Homeobox (HOX genes) | Instruct differentiation and formation of body segments |
| Homebox genes, or HOX genes, are master developmental control genes that | act as the top of genetic hierarchies regulating formation (morphogenesis) of an organism |
| **Each HOX gene is a transcription factor HOX genes are expressed in specific body segments | |
| Similar to SRY, HOX genes can | activate or repress expression of specific genes in a cell. These instruct the differentiation of tissue in specific locations |
| Chemotaxis is the | direct movement of cells towards (chemoattractant) or away (chemorepellent) |
| Cell migration and chemotaxis is vital for | development of many organs |
| Neurons are born where and the migrate where? | deep then migrate above their younger siblings awwwww |
| Ventricular zone | where all brain cells are born (deepest part of the brain) |
| Marginal zone | special cells that secrete reeling, which attracts neurons superficially |
| Lissencephaly is | a rare, gene-linked brain malformation characterized by absence of folds in the cerebral cortex, and an extremely small head Caused by mutation to Reelin gene! |
| Heart development | begins by fusion of 2 tubes ~21 days post conception |
| Congenital heart defects (CHD) are | structural abnormalities of the heart present at birth CHD are the most common congenital disease in newborns 1 in 100 births |
| These septums remain open for as long as | 7 weeks after fertilization |
| ***So, blood from left heart mixed with blood from right heart | |
| ***Incomplete closure of these septums are the most common CHD. The holes may be very small or so large they are lethal (100-200 newborns a year | |
| ***45% of Trisomy 21 patients are born with CHD | |
| Fetal monitoring | Amniocentresis is a test during pregnancy to check embryo’s genetic or chromosomal condition |
| ***As the fetus develops, it expels molecules and living cells into the amniotic fluid. These molecules and cells can be collected and analyzed for various disorders | |
| Used in | higher risk pregnancies, most common advanced material age to screen genetic disorders (trisomy 21) Most efficient and accurate 13-16 weeks post fertilization |
| ***An ultrasound or fetoscopy (camera) are used to guide located fetus and ensure it is not disrupted upon tissue collection | |
| Part of the _____ can also be collected for analyses | chorion, umbilical cord, |
| Earlier or later pregnancy is better? | later |
| In utero intervention | Surgery on baby while still in the womb, or even they can take the amniotic sac outside of the mom's body |
Created by:
liladdoyle