7-Science-Genetics-StudyGuide2 Flashcards
chromosomes
a single tightly wound DNA strand
DNA
Contains all of the info that an organism needs to grow and function
Genes
Sections or segments of DNA
Mutation
A change in DNA
Incomplete Dominance
One gene is not completely dominant of another (red gene+white gene= pink snapdragon)
Co-dominance
Two genes share dominance
Carrier
A person heterozygous for a recessive genetic condition
If two homozygous plants are bred (one green and one albino) what is the ratio of dominant/green to recessive/albino? (Punnet Square)
4:0
What is the ratio of dominant:recessive traits when two heterozygous plants (see prior question) are bred? (Punnet Square)
3:1
For the ration of 3:1 green to albino plants, what fraction was green?
3/4
Why do unicellular organisms divide?
To reproduce
Why do multicellular organisms divide?
To grow and replace old/dead cells
Where is the genetic info in a cell?
Nucleus
When do chromosomes appear in a cell?
During cell division
What happens to the chromosome number in a cell before it divides? Why?
It copies the DNA so that the chromosome number is maintained in the new cells?
How many chromosomes are in each human body cell?
46
Describe the shape of DNA.
Like a twisted ladder, a double helix
What is the backbone (side of the ladder) of DNA?
Sugar (deoxyribose) and phosphate molecules
What are the “ladder rungs” of DNA made of?
Nitrogen bases
What does tymine pair with?
Adenine
What does guannine pair with?
Cytosine
Why do DNA bases pair a certain way?
The bases fit like puzzle pieces, only chemically bond one way
What are sex cells?
Sperm and Egg
Why do sex cells have half the normal amount of chromosomes?
They combine to form 46 chromosomes in a zygote
What sex chromosomes do females have? Males?
F: XX M: XY
What is a karyotype and why is it used?
Photograph of a person’s chromosomes that are cut out, paired and arranged by size; used to examine chromosomes (genes, number, ext.)
If a mutation occurs in a sperm or egg cell, what could happen?
If it was involved in fertilization, the child will inherit that mutation
Favorable mutations depend on the…
environment
List example of following mutations: Helpful; Harmful; Neutral.
Helpful: antibiotic resistance in bacteria
Harmful: cancer/genetic condition
Neutral: Blue Eyes?
In nature vs. nurture, what environmental factor were we testing?
Sunlight
List 4 environmental constants:
Temperature, amount of water, germinating paper, space for growth.
What is the expected ratio of green to albino under normal conditions?
3:1
Can heredity alone ensure a healthy organism?
No. Organisms, like plants, also rely on environmental factors (like water) for proper growth.
Can the environment alone ensure a healthy organism?
No. Some organisms carry mutations that affect normal growth and development.
List 4 environmental factors that could influence human development and health:
Nutrition, exercise, medical care, exposure to pathogens, sleep, ect.
Which critter characteristic showed incomplete dominance (real life example too)?
Nose length, snapdragons (red+white=pink)
Which critter characteristic showed incomplete dominance (real life ex. too)?
spikes, AB blood
Which critter characteristic was influenced by the environment
Tail style, weight, height, intelligence
Which parent’s contribution determines the child’s sex?
male
…conditions have carriers.
recessive
A carrier’s genotype is always…
heterozygous
Why will children of a carrier and a person without alleles for a condition never have the condition
Punnet Square, carrier conditions are always recessive, and all of the kids will get a dominant “normal” allele
Mom: A Dad: A, what are the kid’s possible blood types?
A or O
Mom: AB Dad: O, what are the kid’s possible blood types?
A or B
Mom: AB Dad: AB, what are the kid’s possible blood types?
A, B, or AB
