RAI — 3B — Inheritance, cell division, variation, mutations & evolution Flashcards
Genome?
All genetic information (DNA) of an organism
Gene?
a section of DNA that codes for a specific Protein to influence specific characteristics
Can code for structural protein such as skin
Or can code for functional protein like haemoglobin
Chromosome?
A tightly coiled molecule of DNA in a condensed mass
Nucleus?
Contains chromosomes made of genes in the DNA
Allele?
Different version of the same gene (e.g. hair colour is a gene. Brown hair is an allele of the hair gene)
dominant?
Only one copy of this allele is needed to show the characteristic
recessive?
Needs two copies of the allele to show the characteristic
Heterozygous?
1 copy of each type of allele (e.g. Tt)
homozygous?
2 copies of the same allele
e.g. TT — homozygous dominant
tt — homozygous recessive
phenotype?
The characteristic/trait that is shown/expressed (can roll their tongue)
genotype?
The combination of alleles you have (Rr)
Pedigree shapes and colors:
Circle — female
Square — male
Black — have
White — don’t have
how to remember:
females have a CIRCLE hole
3amo osama has a SQUARE face
black people HAVE dark skin
white people DON’t have dark skin
How to know if it is dominant or recessive in a pedigree?
Dominant traits are likely to be in every generation
Recessive traits are likely to skip generations
How is gender controlled by one pair of chromosomes?
Females possess two copies of the X Chromosome (XX)
Males possess one X and a shorter Y Chromosome (XY)
how to remember:
females get two kisses when you salam
only one man gets a kiss because you only marry one
DNA
Genetic material that gives information about how cells should function
Base pairs held together by hydrogen bonds:
A-T (Adenine, Thymine)
C-G (cytosine, guanine)
Monohybrid?
1 gene determines 1 characteristic
- Eye color
- Hair color
^Discontinuous variation (unaffected by environment, distinct categories)
Polygenic?
Many genes determine a characteristic
- Height
- Skin color
^Continuous variation (influenced by environment, no distinct categories)
Diploid?
Contains two complete sets of chromosomes
23 pairs, 46 in total
Diploid – Double
Haploid?
Contain only one set of chromosomes
23 in total
HAploid — HAlf
Mitosis
Cell Division that produces two genetically identical, diploid daughter cells
how to remember:
mitosis (my toe sis) = identical daughter cells
Function of mitosis
- tissue repair
- growth
- asexual reproduction
- development (zygotes undergo mitosis to develop into embryos)
Process of mitosis
- DNA replication to form two copies of each chromosome in the cell (now it has 46 pairs of chromosomes)
- Then mitosis occurs and the cell splits into two daughter cells
- each daughter cell has 23 pairs of identical chromosomes (diploid)
meiosis?
produces four haploid gamete cells (reproductive cells — egg and sperm) that are not genetically identical
function of meiosis?
- for reproduction, haploid cells are needed to to contain only one copy of each chromosome (egg (23) + sperm (23) = zygote (43))
process of meiosis
- meiosis has two stages of division
- chromosomes in a parent cell make identical copies of themselves
- similar chromosomes pair up and sections of dna are swapped
- pairs of chromosomes divide
- then they divide again to make four haploid cells
Variation?
Differences in between individuals particularly in the same species
- Can be genetic (eye/hair color, blood type, inherited disorders) or environmental (envir. conditions (temp, weather), predators/pathogens, presence of food) or both
Mutation?
a rare, random change in genetic material that can be inherited.
Natural selection?
VOSSIG
V — variation (individuals within a species differ. Caused by mutation)
O — over-production (all organisms over-produce which limits the number of resources available)
S — struggle for existence (not enough resources)
S — survival of the fittest (one with the mutation survives)
I — Inherit (the ones who survive reproduce and pass down their alleles)
G — gradual change (happens over many generations)
Antibiotic resistance?
-You start taking an antibiotic
-Some bacteria are susceptible to (killed by) the antibiotic. Some are resistant to (not killed by) antibiotic
-The susceptible (weak) bacteria are killed first
-Only resistant (strong) bacteria are left
-You stop taking the antibiotic
-The resistant (strong) bacteria reproduce
-The resistant (strong bacteria are now more common
- If you take the antibiotic again, it won’t work because all the bacteria are resistant
Cell division process names
- Prophase - chromosomes replicate
- Metaphase - middle (chromosomes line up in the middle)
- Anaphase - chromosomes move away from each other
- Telophase - two new cells form
- For meiosis it does steps 1-4 twice
