3B - Cell Division, Genetics, and Molecular Biology

Question 1

What is pangenesis

Answer 1

Pangenesis = old theory from ancient greece where tiny particles called gemmules from all parts of the body travel through blood 🩸 to the reproductive organs 👶.
Babies inherit a mix of these gemmules from their parents.
Invented by Darwin 🧔🏻 but proven wrong 🚫 — real inheritance happens through DNA in cells, not gemmules! 🧬

Question 2

Whats the chromosome theory of inheritence

Answer 2

Genes are located on chromosomes!
Chromosomes move during meiosis to pass genes from parents to offspring. 🧑‍🤝‍🧑
Explains Mendel’s laws using visible stuff (chromosomes under a microscope 🔬).
Sutton and Boveri proposed it! 🧠

Question 3

What does dominant mean in genetics?🧬

Answer 3

A dominant trait appears even if there’s only one copy of the dominant gene. 💥
It masks recessive traits.
Shown with a capital letter (ex: A).
If you have A or Aa, you show the dominant trait. 😎

Question 4

What does recessive mean in genetics?

Answer 4

A recessive trait only appears if you have two copies of the recessive gene. 🫣
It gets hidden by dominant genes.
Shown with a lowercase letter (ex: a).
Only aa shows the recessive trait. ✅

Question 5

What is a Punnett Square used for?

Answer 5

A Punnett Square predicts the possible gene combinations from two parents! 🧬👶
Mix parents’ alleles across a grid to see possible traits.
Example: Aa x Aa = 75% dominant trait, 25% recessive. 🎲

Question 6

What is a phenotype? 👀🎨

Answer 6

A phenotype is the physical traits you can see, like eye color 👁️ or height 📏.
It’s the result of your genotype (genes) + sometimes environment 🌞.
P = Physical!

Question 7

What is a test cross used for? 🕵️‍♀️🌱

Answer 7

A test cross checks if an organism showing a dominant trait is homozygous (AA) or heterozygous (Aa).
Breed it with a recessive (aa).

All dominant babies = homozygous.

Some recessive babies = heterozygous. 🧬

Question 8

What does true breeding mean? ✍️🌱

Answer 8

True breeding means an organism is homozygous (AA or aa) and always produces offspring with the same trait. 👶
Mendel used true-breeding pea plants to study inheritance! 🌱

Question 9

What is the Parental Generation (P generation)? 👩‍❤️‍👨🧬

Answer 9

The P generation is the first generation of parents in a genetic cross.
They can be homozygous or heterozygous.
Their offspring are the F1 generation (first kids!). 💥👶

Question 10

What is the F1 Generation? 👶🧬

Answer 10

The F1 generation is the first generation of offspring from the P generation.
They’re usually heterozygous (like Tt) and show the dominant trait. 👑
F1 = first squad of kids!

Question 11

What is a Monohybrid Cross? 🔬🌱

Answer 11

A monohybrid cross is a cross between two organisms that differ in one trait. 🧬
Used to study dominant and recessive alleles for that trait.
Example: Rr × Rr for flower color.

Question 12

What is the Law of Segregation? 🔬

Answer 12

Mendels first law of inheritence

The Law of Segregation states that during meiosis, the two alleles for a trait separate so that each gamete carries only one allele for each gene. 🧬
Each parent randomly passes one allele to their offspring. 💥 (Parent either gives A or a)

Question 13

What is the Law of Independent Assortment? 🔬

Answer 13

Mendels second law of inheritence

The Law of Independent Assortment says that genes for different traits are inherited independently of each other.
The inheritance of one trait doesn’t affect the inheritance of another. 🧬
It only applies if the genes are on different chromosomes or far apart.

Question 14

hybrid

Answer 14

A hybrid is the offspring of two organisms that differ in at least one trait. 🧬
It’s usually heterozygous (like Aa) and has a mix of alleles. 💥
Example: Tt hybrid plant (tall × short).

Question 15

homogenous

Answer 15

Homogeneous means having two identical alleles for a trait, either AA (homozygous dominant) or aa (homozygous recessive).
It’s like having matching socks 🧦 — no mix, just the same!

Question 16

homozygous

Answer 16

Heterozygous means having two different alleles for a gene, like Aa.
One dominant and one recessive — it’s a mix-and-match pair. 🧦
The dominant trait will show! 💥

Question 17

genotype

Answer 17

A genotype is the genetic makeup of an organism — the set of alleles inherited for a trait.
It can be homozygous (AA or aa) or heterozygous (Aa).
The genotype determines the potential for phenotype! 💥

Question 18

complete dominance

Answer 18

Complete dominance happens when the dominant allele completely masks the effect of the recessive allele.
If the genotype is AA or Aa, the dominant trait will show!
aa is the only time the recessive trait shows. 💥

Question 19

dihybrid cross

Answer 19

A dihybrid cross is a genetic cross between two organisms that looks at the inheritance of two different traits.
It uses a Punnett square with 16 boxes to show all the possible allele combinations. 💥

Question 20

co-dominance

Answer 20

Co-dominance occurs when both alleles for a trait are equally expressed in the phenotype.
Example: AB blood type — both A and B alleles show up equally! 💥

Question 21

What is incomplete dominance? 🧬

Answer 21

Incomplete dominance happens when the heterozygous genotype results in a blended or intermediate phenotype.
Example: Red (RR) × White (WW) = Pink (RW) flowers. 🌸💥

Question 22

Selective breeding

Answer 22

Selective breeding is when humans choose parent organisms with specific traits to produce offspring with those traits.
Example: Breeding poodles to get more puppies with curly fur. 🐩

Question 23

Barr body

Answer 23

A Barr body is an inactive X chromosome found in female mammals. It’s a chilled-out X that doesn’t contribute to the cell’s function.
In males (XY), there is no Barr body because they only have one X chromosome. 💥

Question 24

chromosome mapping

Answer 24

Chromosome mapping is the process of finding the location of genes on a chromosome.
Genes that are closer together are more likely to be inherited together.
It’s like a map showing where each gene is located. 🗺️

Question 25

continuous trait

Answer 25

A continuous trait is a trait that shows gradual variation across a range. It is controlled by multiple genes and often influenced by the environment. Example: Height, skin color 🌈

Question 26

Crossing over

Answer 26

Crossing over is when homologous chromosomes exchange pieces of their genetic material during meiosis. It creates new combinations of alleles and increases genetic diversity. 💥 It happens in prophase I of meiosis.

Question 27

What is the gene-chromosome theory? 🧬

Answer 27

The gene-chromosome theory states that genes are located on chromosomes. During meiosis, chromosomes are separated, and they carry the genes that are inherited by the offspring. It connects Mendel’s laws to the behavior of chromosomes during cell division. 💥

Question 28

Linked genes

Answer 28

Linked genes are genes located close together on the same chromosome and tend to be inherited together during meiosis. They’re like BFFs who rarely split up! 👯‍♀️

Question 29

What is map distance in genetics? 🧬

Answer 29

Map distance is the measurement of how far apart two genes are on a chromosome. It’s measured in centimorgans (cM), with 1 cM equaling a 1% recombination frequency. The greater the map distance, the more likely they are to be separated by crossing over. 🗺️

Question 30

Recombination frequency

Answer 30

Recombination frequency is the percentage of offspring that inherit recombined chromosomes due to crossing over during meiosis. A higher recombination frequency means genes are further apart, and less likely to be inherited together. A lower recombination frequency means genes are closer together. 🔄

Question 31

What is a map unit? 🧬

Answer 31

A map unit is a unit of genetic distance that equals a 1% recombination frequency between two genes. 1 map unit = 1% recombination frequency. It helps measure how far apart genes are on a chromosome. 📏

Question 32

multiple alleles

Answer 32

Multiple alleles are when a gene has more than two versions (alleles) in the population. Each individual can only have two alleles (one from each parent). Example: Blood type (A, B, O) is controlled by three alleles: IA, IB, i.

Question 33

What is the order of dominance? 🧬

Answer 33

The order of dominance refers to how dominant alleles always show their traits, while recessive alleles are only expressed if both alleles are recessive (homozygous). Dominant alleles mask the expression of recessive alleles. 👑

Question 34

What is the parental type in genetics? 🧬

Answer 34

he parental type refers to the genetic traits (or phenotype) of the original parent(s) in a genetic cross. It’s the non-recombined trait set — what the parents look like before any crossing over happens. 👨‍👩‍👦

Question 35

What are polygenes? 🧬

Answer 35

each gene contributes a small amount to the overall trait. These traits are usually continuous, meaning they show a range of variations (e.g., height, skin color). 💪

Question 36

polegenic

Answer 36

Polygenic inheritance is when multiple genes contribute to a single trait, leading to a range of phenotypes. Examples include height, skin color, and weight. The more genes involved, the more variation in the trait!

Question 37

What is recombinant type? 🧬

Answer 37

Recombinant type refers to offspring that inherit new combinations of alleles due to crossing over during meiosis. They have different traits than the parental types. 🔄

Question 38

sex linked traits

Answer 38

Sex-linked traits are traits controlled by genes located on the X chromosome. Males (XY) need only one copy of the allele to show the trait. Females (XX) need two copies of the recessive allele to show the trait. 💡

Question 39

Autosomal inheritance

Answer 39

Autosomal inheritance refers to the inheritance of traits controlled by genes located on autosomes (chromosomes 1–22). Autosomal dominant traits require one dominant allele to show up. Autosomal recessive traits require two recessive alleles to be expressed. 🙌

Question 40

pedigree

Answer 40

A pedigree is a family tree that shows how a genetic trait is passed down through multiple generations. Squares = males Circles = females Filled symbols = trait is present Empty symbols = trait is absent Used to track dominant, recessive, or X-linked traits. 🙌

Question 41

wild type

Answer 41

Wild type refers to the most common or normal form of a trait or gene in nature. It’s the baseline version of a trait before any mutations or breeding changes. 🌍