Inheritance

Question 1

Define Genetics:

Answer 1

-The study of heredity and variation in living things.

Question 2

What do Gametes transfer?

Answer 2

-Gametes transfer hereditary characteristics.

Sperm+egg=zygote -> organism

Question 3

What characteristics do organisms inherit?

Answer 3

-Each organism inherits characteristics from its parents that make it that type of organism. (e.g: dog, cat, human…)

-Each organism also inherits characteristics that make it unique (that 0.1% of DNA that makes you special :)

Question 4

Define a Genome:

Answer 4

-A complete set of genes or genetic material present in a cell or an organism.

Question 5

What is a somatic cell?

Answer 5

-Any cell of a living organism other than reproductive cells.

-body cells (diploid)

Question 6

Define Gametes:

Answer 6

sex cells (haploid)

Question 7

what does each somatic cell have?

Answer 7

-Each somatic cell (except for red blood cells) has a complete set of instructions.

Question 8

Are all genes activated to synthesize particular proteins?

Answer 8

-NO, only certain genes are activated in certain cells to synthesize particular proteins for the functioning of that cell.

Question 9

Who was the father of genetics & where did he work?

Answer 9

Gregor Mendel

-He worked at a monastery and at a high school.

Question 10

How did Mendel formulate the basic laws of genetics?

Answer 10

-He tended the monastery garden, grew peas, and became interested in the traits that were expressed in different generations of peas.

Question 11

Why did Mendel choose peas to do his experiments on?

Answer 11

-Grow Quickly -> results can be obtained quickly.
-Easily identifiable traits.
-Peas produce a large number of offspring -> makes results easier to verify
-Naturally self-pollinating ->control crosses by hand

Question 12

List the contrasting characteristics of peas:

Answer 12

-tall/short
-smooth/wrinkled seeds
-yellow/green seeds
-yellow/green pods
-inflated/constricted pods
-purple/white flowers
-axial/terminal flowers

Question 13

What is Cross-Pollination?

Answer 13

-pollen is transferred from the anther of a flower of one plant -> to the stigma of a flower of another plant, of the same species.

Question 14

What is a monohybrid cross?

Answer 14

A monohybrid cross is between organisms that differ in one respect.

Question 15

What does “true breeding” imply?

Answer 15

-When parent plants with the same characteristics (homozygous for genes) have offspring, the offspring would be identical to the parents.

Question 16

Describe the P1 cross:

Answer 16

-Cross-pollinate two plants with differing traits (tall/short) -> this is called the P1 generation (parents)

-Their offspring (F1 generation) all grew to be tall.

• what happened to the short characteristic?

Question 17

Describe the F1 cross:

Answer 17

-F1 generation self-pollinates, creating the F2 generation.

-In the F2 generation, “shortness” reappeared.
75% - tall & 25% short

-so shortness didn’t completely disappear.

Question 18

What are hybrids?

Answer 18

-They are the offspring of crosses between parents with different traits.

Question 19

Define Alleles:

Answer 19

-The different forms of the same gene

Question 20

Define Locus:

Answer 20

-Position of a gene on a chromosome

Question 21

What’s the difference between Haploid and Diploid?

Answer 21

-Haploid cells are those that only have a single set of chromosomes (n)

-Diploid cells have two sets of chromosomes (2n)

Question 22

What is Heterozygous vs Homozygous?

Answer 22

Homozygous - two identical alleles

Heterozygous - two different alleles

Question 23

Define Phenotype:

Answer 23

-The observable physical or biochemical characteristics of an organism.

Question 24

How is the phenotype determined?

Answer 24

-The phenotype is determined by both the genotype & environmental influences.

Question 25

Define Genotype:

Answer 25

-The genotype is the genetic makeup of an organism, representing certain alleles it possesses for a particular trait. E.G: homozygous dominant (TT); heterozygous (Tt)

Question 26

Explain Dominant Vs Recessive genes:

Answer 26

Dominant - trait will appear in phenotype if present in genotype. Recessive - trait will be masked by the presence of a dominant gene; will only appear if homozygous.

Question 27

What is complete dominance?

Answer 27

-If dominant allele is present, it will be expressed. -If recessive allele is present. it will only be expressed if homozygous.

Question 28

Describe Mendel's law of segregation:

Answer 28

-During meiosis, allele pairs (found on homologous chromosomes) separate so that gametes have a single allele for each characteristic.

Question 29

Describe Mendel's Law of Dominance:

Answer 29

-In a cross of parents that are "pure" for contrasting traits, only the dominant trait will appear in the phenotype of the offspring. -P1 cross

Question 30

Describe Mendel's law of independent assortment:

Answer 30

-The alleles of different genes segregate randomly and independently from one another during meiosis.

Question 31

What do gonosomes do?

Answer 31

-sex determining chromosomes. -also carry other genes - sex-linked genes

Question 32

Describe the Y chromosome:

Answer 32

-Y chromosome is small & carries almost no other genes apart from those coding for "maleness"

Question 33

Describe the X chromosome:

Answer 33

-X chromosome is a large chromosome carrying many other genes, including those coding for "femaleness"

Question 34

Alleles carried on the "non sex" part of the X gonosome are called?

Answer 34

-Alleles carried on the "non sex" part of the X gonosomes are called X-linked or sex-linked alleles.

Question 35

Name two sex-linked disorders:

Answer 35

-red-green colour blindness -Hemophilia

Question 36

Describe red-green colour blindness:

Answer 36

-Recessive gene carried on X chromosomes -Visual defect due to absence of a photo-pigment on the retinal clones -> can't distinguish between red & green.

Question 37

Describe Haemophilia:

Answer 37

-Recessive allele carried on X chromosome -Inability to clot blood properly, leading to frequent, excessive bleeding and bruising

Question 38

Define Polygenic:

Answer 38

-Polygenic is a trait condition that's controlled by multiple genes.

Question 39

What are genetic counsellors?

Answer 39

-Genetic counsellors are health professionals who study family and medical histories to analyse inheritance patterns & the risk of problems occurring.

Question 40

What is a family tree & what can it predict?

Answer 40

-A family tree shows the genotypes & phenotypes of several generations of individuals in a family. -It can be used to predict if a couple is likely to pass on a genetic disorder. -The carriers are shown too.