3 - GENES Flashcards
how are genes structural?
they are sections of dna
statement:
- genes are evolutionary as they are the hereditary
- carry information down generations
-
what is the passive stage of genes?
chromatin strands densely packed
what is the active stage of genes?
- DNA is in loose chromatin strands
- wrapped around a histone protein
what is a chromosome?
tightly coiled band of chromatin
information:
cells + chemical soup
- cells are chemical factories
- thick chemical soup inside membrane
- and outside membrane
- exchange chemicals through cell membrane
- involves proteins
what are proteins?
4 things
1 - complex molecules (very long, highly folded amino acid chains)
2- building blocks of cell structures
3 - active ingredient that ‘work’ on inert biological molecules (e.g. enzymes)
4 - produced in response to chemical environment
what does ‘activating’ a gene mean?
- gene expression!
- causing the production of the protein
- because genes code for specific proteins
- some genes may only indirectly contribute to protein synthesis - they may not code for a protein directly themselves
how can genetic rules produce a large variety of outcomes?
due to:
- the exact environment
- the exact starting point
- environment changes the rules as changes which rules are active
what makes a genetic code a rule book, rather than a blueprint?
because it contains instructions on how to respond to the environment
- some responses alter a cells form or function
- some alter which genes (rules) are active - thereby changing a cells response to the environment
are genes and the environment linked?
yes!
only the two together can cause the outcome
genes are the means to respond to the environment
what are sequicygotic twins?
twins fertilised by two sperm cells
what type of enzymes aids the production (genesis) of steroids?
steroidogenic enzymes
characteristics of steroids
2 things
1 - fat-like substances
2 - easily pass through cell membranes
how many types of steroids?
2 (sex hormones and corticosteroids)
which sex hormones promote the development of female sex characteristics? (2)
estrogens and progesterone
which sex hormone promote the development of male sex characteristics?
androgens
what is the function of corticosteroids
control stress response
+ sugar metabolism
what are the sources of steroids?
gonads + adrenal gland
where is the adrenal gland located?
on top of the kidneys
function of steroids (4 things)
1 - modify gene expression (activate genes)
2 - bind to specific receptor molecules inside of cell (receptor molecules floating around inside of cell - if encounter specific hormone = bind to it, and then bind to specific gene)
3 - receptor molecules bind to specific gene and activates it (must enter nucleus first)
4 - proteins will be produced
how many chromosomes in a human?
46 chromosomes (23 pairs)
- 22 pairs of autosomes (members of each pair very similar)
- 1 pair of sex chromosomes (can be similar or dissimilar)
how many chromosomes in a human gamete?
23 chromosomes - one from each pair
- 22 autosomes
- 1 chromosome (X or Y)
what is fertilisation?
combination or the maternal and paternal half sets
